Gale Virtual Reference Library (GVRL) contains a large variety of reference books available for reading online. One of the subjects we have is fashion. You can look through the complete range of titles for adults here: Gale Virtual Reference Library Primary Research.
Some individual titles are Clothing and Fashion: American Fashion from Head to Toe, The Encyclopedia of Clothing and Fashion, Fashion Fads through American History: Fitting Clothes into Context, Fashion, Costume, and Culture, ed. 2: Clothing, Headwear, Body Decorations, and Footwear Through the Ages, and World Clothing and Fashion: An Encyclopedia of History, Culture, and Social Influence.