ARBA , Walford's , D.+B.Rare Book , D.+ B. Special Collection , World Cataloge , Publisher Directory. What are them? I need information about them.

ARBA is American Reference Books Annual: http://www.arbaonline.com/

Walford's is a guide to different kind of reference material: http://www.abe.com.pl/html/english/details.php?id=1856040151

World Catalogue is the world's largest network of library content and services: http://www.worldcat.org/

Publisher Directory is a directory of information about publishers.

D.+B. Rare Book and D.+B. Special Collection are unfamiliar to me, but I think they are book catalogues.