[Impact factor and certification].
Völcker
H E
HE
D015706:Bibliometrics; D004502:Education, Medical, Continuing / Q000379:methods / Q000706:statistics & numerical data; D005858:Germany; D006801:Humans; D009885:Ophthalmology / Q000706:statistics & numerical data*; D010506:Periodicals as Topic / Q000706:statistics & numerical data*; D011643:Publishing / Q000592:standards* / Q000706:statistics & numerical data; D014481:United States