title: A study on literature obsolescence and core journals' cost-benefit in citations of the 'Scientific Medical Journal of Ahwaz'.
abstract: BACKGROUND
  One of the methods of identifying core and popular resources is by citation evaluation. Using citation evaluation, the librarians of the Acquisition Department can use quantitative methods to indentify core and popular resources among numerous information resources and make serious savings in the library's budget, by acquiring these core resources and eliminating useless ones. The aim of this study is assessing literature obsolescence and core journals' cost-benefit in citations of the 'Scientific Medical Journal of Ahwaz'.
  
  
  METHODS
  This study is a descriptive and cross-sectional survey that uses citation analysis. Sampling is objective sampling from all documents from years 1364 (1985) to 1385 (2006), and the population comprises of 6342 citations of the articles published in 'Scientific Medical Journal of Ahwaz'. Data collection is done through referring to the original documents and the data is analyzed using the Excel software, and for descriptive and analytical statistics the cost-benefit formula and Bradford law formula are used.
  
  
  RESULTS
  Findings showed that the average citation for each document in the 'Scientific Medical Journal of Ahwaz' was 15.81. The average citation to international sources was 14.37, and the average citation to national sources was 1.44. The literature obsolescence of Farsi documents in this study was 15 years, while it was equal to 20 years for English documents. The highly cited Farsi journals were (sorted based on citation in descending order): 'Scientific Medical Journal of Ahwaz', 'Daroudarman', 'Nabz,' and 'Journal of Medical School, Shahid Beheshti University of Medical Sciences'. The highly cited English journals were (sorted based on citation in descending order): 'Pediatrics', 'The New England Journal of Medicine', 'Gastroenterology' and 'Medicine'. All of these four journals are part of the ISI database and have good impact factors in the Journal Citation Reports (JCR). Also their cost-benefit was reasonable based on the frequency of their use.
  
  
  CONCLUSIONS
  The authors of the investigated journal were more inclined to use international references. The resources used by the authors of this journal are relatively obsolete and the authors ought to use more up-to-date resources. The subscription for high citation English and Farsi journals is still available in this university. Also the authors of this journal have used accredited ISI journals as their resource, which is a sign of the credibility for the 'Scientific Medical Journal of Ahwaz'.
authors.affiliation: School of Medical Library and Information Science, Health Information Technology Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Firoozeh
authors.initials: F
authors.lastname: Zare-Farashbandi
authors.affiliation: Medical Library and Information Science, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
authors.forename: Parastoo Parsaei
authors.initials: PP
authors.lastname: Mohammadi
keywords: Bradford Law; Scientific Medical Journal of Ahwaz; citation analysis; core journals; cost-benefit; literature obsolescence