G and L Postcards WB: Offers a catalog of postcards with an early 20th century Halloween theme, geared towards collectors and dealers.
Island Curio Authentic Hawaiian Postcards: Keith J. Steiner's book on postcards of Hawaii between 1900 and 1915. Also includes a catalog of Island cards.
Valentines Valentines Valentines: Katherine Kreider's three books on antique valentines.