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NLM Technical Bulletin

NLM Technical Bulletin 1998 Mar-Apr; 301



In This Issue:

Technical Notes - e1

Associations Switch to Free Web Access - e2

dotPubMed's Citation Matcher - e3


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PubMed's Citation Matcher

Using the PubMed Citation Matcher
Citation Matcher offers an easy way to locate a citation even when you lack complete bibliographic information (e.g., author, title, year). The Citation Matcher allows you to enter any or all of the following bibliographic elements: journal title, date, volume, issue, page, author into a search form to try to find your specific citation.

Initially, the National Center for Biotechnology Information developed the Citation Matcher as a retrieval tool to allow publishers to find the PubMed ID or the MEDLINE® UI of a citation without having to use (or know) PubMed's search and syntax rules. Publishers could then establish links from their Web sites to the citation in PubMed using the ID or UI. Effective January 26, 1998 with the PubMed 2.0 system update, the once well-hidden Citation Matcher was elevated from the Overview section to a more prominent link on the Home page grey sidebar.

Note: For a complete listing of PubMed 2.0's new features and enhancements (e.g., MeSH Browser, Loansome Doc, new search fields), click on the New/Noteworthy link on the PubMed Home page sidebar.

What's the Advantage of Using the Citation Matcher?
While constructing a search strategy for a specific citation in any of PubMed's search modes is easily done, the Citation Matcher's interface is quick and user-friendly. And Citation Matcher is a vast improvement to the multi-step search process required in ELHILL given the same amount of information.

PubMed includes all of MEDLINE (1966 to present) and PREMEDLINE in a single file. Compare this to ELHILL with its segmented file structure, where the search for a specific citation (depending on the information provided by the patron ) may require searching in one or more of the Backfiles or PREMEDLINE in addition to the current MEDLINE file.

PubMed allows you to search directly for the first page number, volume, and issue. Using the fill-in-the-blanks search screen shown in Figure 1, means you don't need to remember the field qualifiers for these data elements and you don't have to know any special search commands to run your search. Compare this to ELHILL, where because the Pagination (PG), Volume Issue (VI), and Issue/Part/Supplement (IP) fields are not directly searchable, the proximity operator CONTAINS must be used when constructing a search strategy with these elements. (The CONTAINS command may be used in place of the STRINGSEARCH (TS) function on ELHILL.)

How to use the Citation Matcher
To use the Citation Matcher click on the link from PubMed's Home page sidebar to display the Citation Matcher for Single Articles as shown in Figure 1. In this screen, enter the bibliographic data you have as instructed on the screen, and click on Search. For example, with just the following information: author, journal title, volume and pages (article by Kearns in volume 36 of the Journal of Clinical Microbiology, pages 604-605) you can easily find your citation. Enter these data in the Journal, Volume, First page (Page), and Author fields (boxes) as in Figure 1 and click on Search. The search result is a direct match as shown in Figure 2.


Figure 1 - Citation Matcher

Screen capture of citation matcher

Figure 2 - Citation Matcher Results

Screen capture of Citation Matcher Results

In the Citation Matcher, it is not required to enter data in every field (box). The Citation Matcher will combine (AND) together all the data entered using PubMed's search and syntax rules and run the search strategy shown in Figure 3. You may see this strategy displayed by clicking on the Details button from the initial citation display (Document Summary Page). The Details button is visible in the PubMed search screen shown in Figure 2. The more fields (boxes) that are completed, the greater the likelihood of a single match, especially if the first page number is included. However, if no match is found try omitting various pieces of information one at a time because one piece may be incorrect and, therefore, preventing the match.


Figure 3 - Search Strategy as shown in the Details Screen

Screen capture of Search Strategy as shown in the Details Screen

To compare, Figure 4 shows a sample ELHILL search strategy to find the same citation that is searched for in Figure 1 in the PubMed Citation Matcher.


Figure 4 - Searching for the Citation in ELHILL

YOU ARE NOW CONNECTED TO THE MEDLINE (1995 - 98) FILE.                          
                                                                             
SS 1 /C?                                                                        
USER:                                                                           
j clin microbiol (ta) contains 604 (pg)                                         
                                                                              
PROG:                                                                           
*NONE-      You now have to guess at what file to try, 
              PREMEDLINE or a Backfile?                 
                                     
SS 1 /C?                                                                        
USER:                                                                           
file premed                                                                     

PROG:                                                                           
YOU ARE NOW CONNECTED TO THE PREMEDLINE FILE.                                   
NOTICE: THESE PRELIMINARY, UNINDEXED CITATIONS 
HAVE NOT GONE THROUGH NLM'S QUALITY CONTROL PROCESS.                                                  
                                                                               
SS 1 /C?                                                                        
USER:                                                                           
j clin microbiol (ta) contains 604 (pg)                                         
                                                                                
PROG:                                                                           
SS (1) PSTG (1)                                                                 
                                                                                
SS 2 /C?                                                                        
USER:                                                                           
prt                                                                             
                                                                                
PROG:                                                                           
                                                                              
1                                                                               
UI   -    98126266                                                                  
AU   -    Kearns AM                                                                 
AU   -    Freeman R                                                                 
AU   -    Steward M                                                                 
TI   -    Evaluation of a rapid air thermal cycler for 
            detection of Mycobacterium tuberculosis 
            [letter] [In Process Citation]                               
SO   -    J Clin Microbiol 1998 Feb;36(2):604-5

Additional Advantages to using the Citation Matcher
The Citation Matcher can also be used to retrieve citations indexed from a specific issue, volume, or year of a journal along the lines of a "Table of Contents" search. For example, to retrieve citations indexed from volume 335, issue 26 of the New England Journal of Medicine, just enter this information in the Volume, Issue and Journal boxes and click on Search as shown in Figure 5. The Citation Matcher will retrieve the citations to indexed items from the New England Journal of Medicine, 335(26). There are 27 items. After you click on the Details button from the Document Summary Page, the Details box (shown in Figure 5A) allows you to see that the full title is translated into the title abbreviation for search purposes. Unlike ELHILL, you do not have to know the MEDLINE title abbreviation to run your search; the computer's translation table will find the title abbreviation for you. On ELHILL, to retrieve this same set of citations it is necessary to construct searches using the CONTAINS operator as shown in Figure 6.


Figure 5 - Finding all Citations from a Single Issue

Screen capture of Finding all Citations from a Single Issue

Figure 5A - Full Journal Title Translated to Title Abbreviation as shown in Details Box

Screen capture of Full Journal Title Translated to Title Abbreviation as shown in Details Box

Figure 6 - ELHILL Search Strategy to Find All Citation From a Single Issue Using Contains Operator

SS 1 /C?                                                                        
USER:                                                                           
n engl j med (ta)                                                               
                                                                              
PROG:                                                                           
SS (1) PSTG (4285)                                                              
                                                                                
SS 2 /C?                                                                        
USER:                                                                           
1 contains 335 (vi)                                                             
                                                                                
PROG:                                                                           
NOTE: YOUR PROXIMITY SEARCH OF 4,285 RECORDS MAY CAUSE MANY 
  TIME OVERFLOWS.                                                                      
TIME OVFLW: CONT? (Y/N)                                                         
                                                                                
USER:                                                                           
y                                                                               
                                                                                
PROG:                                                                           
SS (2) PSTG (647)                                                               
                                                                                
SS 3 /C?                                                                        
USER:                                                                           
2 contains 26 (ip)                                                              
                                                                                
PROG:                                                                           
SS (3) PSTG (27)                                                                
                                                                                
SS 4 /C?                                                                        
USER:                                                                           
prt                                                                            
                                                                                
PROG:                                                                           
                                                                                
1                                                                               
UI   -   97115916                                                                  
AU   -   Brennan TA                                                                
AU   -   Sox CM                                                                    
AU   -   Burstin HR                                                                
TI   -   Relation between negligent adverse events and the 
         outcomes of medical-malpractice litigation [see 
         comments]                             
CM   -   Comment in: N Engl J Med 1997 Jun 5;336(23):1680; 
         discussion 1680-1                                                                    
SO   -   N Engl J Med 1996 Dec 26;335(26):1963-7 



Note: Please be aware of these important factors about a PubMed MEDLINE search for the contents of a particular journal issue:

  • Out of the more than 3,900 journals currently indexed for MEDLINE, approximately 350 are selectively indexed. For selectively indexed titles, not all articles will be present, just the ones selected from an issue.
  • Certain portions of a journal, such as News or Letters, may not be supplied routinely by some publishers who provide NLM with electronic citation data. Although the missing items will be added during the indexing operation, they will not be present as in-process records. Also, for journal data supplied electronically by publishers PubMed will contain citations to out-of-scope articles even though those articles are not indexed for MEDLINE.
  • Even for journals that are indexed cover-to-cover, the NLM may not select certain sections, such as book reviews, as indexable "articles."
--prepared by Rhonda Allard
MEDLARS Management Section

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