1-2) Enjoy Your Chihuahua (1967) by Earl Schneider is 32 pages long, with color plates. The same author's Know Your Chihuahua (1967) has twice as many pages and more photos. Schneider published pet-books of all sorts in the 1950s, distributed exclusively through petshops.
3) Chihuahua: Artlist Collection, The Dog Postcard Booklet (2003) edited by Koji Tomono and Daisuke Ogura, one of several volumes for various breeds.
4) Pepino (2002) by Lisa Karlskin, a children's book starring a chihuahua, designed to teach kids about animal shelters.