A few resources for researching fashion and the fashion industry:

Encyclopedias
Berg Fashion Library, includes the Encyclopedia of World  Dress and Fashion (Oxford, 2010) and many other books about fashion.

Encyclopedia of Clothing and Fashion (Scribner's 2005).

Journals
Vogue Archive-issues from 1892 to the present

WWD (Women's Wear Daily) – current paper issues are in the  Business Library, full-text (no images) is available from numerous sources, the microfilm backfile is in Business

A few other ejournals, including Fashion Theory

Databases: The Ebscohost Research Databases, provide an excellent multidisciplinary search.

Books:
Check CLIO for books.  Most books about designers are in Avery Library; general works about clothing and dress will be in Butler, Barnard, or Business.   Try WorldCat to search beyond Columbia's collections.   If material is not available at Columbia, try Borrow Direct or ILL.  If you need to use the FIT library, come to the Butler Reference Desk.

If you have any questions about researching fashion, please Ask a Librarian.