Descripción
Publicado:Began with: 1991.
Frecuencia de Publicación:Every eighteen months
Formato:Master and use copy. Digital master created according to Benchmark for Faithful Digital Reproductions of Monographs and Serials, Version 1. Digital Library Federation, December 2002.
ISSN:19990529
Publicación relacionada:Issued also <1995-> in floppy disk ed.; issued also <1995-> in CD-ROM ed. which combines surveys from many countries.