http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Ulrich's international periodicals directory
Kept up to date between editions 1972-76 by: Bowker serials bibliography supplement; 1977-Sept. 1985 by: Ulrich's quarterly; Dec. 1985-June 1988 by: Bowker international serials database update; Sept. 1988- by: Ulrich's update.
Bowker international serials database update
Irregular serials & annuals; an international directory
Ulrich's periodicals directory (New Providence, N.J.)