title: An application of Bradford's law: identification of the core journals of pediatric neurosurgery and a regional comparison of citation density.
abstract: OBJECTIVE
  Bradford's law describes the number of core journals in a given field or subject and has recently been applied to neurosurgery. The objective of this study was to use currently accepted formulations of Bradford's law to identify core journals of pediatric neurosurgery. An additional analysis was completed to compare regional dependence on citation density among North American and European neurosurgeons.
  
  
  METHODS
  All original research publications from 2009 to 2013 were analyzed for the 25 top publishing pediatric neurosurgeons in North America and Europe, which were sampled to construct regional citation databases of all journal references. Regional differences were compared with each database. Egghe's formulation and the verbal formulation of Bradford's law were applied to create specific citation density zones and identify the core journals.
  
  
  RESULTS
  Regional comparison demonstrated a preference for the Journal of Neurosurgery and Child's Nervous System, respectively, but four of the top five journals were common to both groups. Applying the verbal formulation of Bradford's law to the North American citation database, a pattern of citation density was identified across the first three zones. Journals residing in the most highly cited first zone are presented as the core journals.
  
  
  CONCLUSIONS
  Bradford's law can be applied to identify the core journals of neurosurgical subspecialties. While regional differences exist between the most highly cited and most frequently published in journals among North American and European pediatric neurosurgeons, there is commonality between the top five core journals in both groups.
authors.affiliation: College of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA.
authors.forename: Garrett T
authors.initials: GT
authors.lastname: Venable
authors.forename: Brandon A
authors.initials: BA
authors.lastname: Shepherd
authors.forename: Mallory L
authors.initials: ML
authors.lastname: Roberts
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Taylor
authors.forename: Nickalus R
authors.initials: NR
authors.lastname: Khan
authors.forename: Paul
authors.initials: P
authors.lastname: Klimo
mesh_terms: D016206:Databases, Bibliographic / Q000706:statistics & numerical data; D005060:Europe; D006801:Humans; D055811:Journal Impact Factor; D009493:Neurosurgery; D009656:North America; D010372:Pediatrics; D011643:Publishing; D012189:Retrospective Studies
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