1) Chihuahuas (1983) by Beverly Pisano, an often reprinted book with various covers.

2) The Chihuahua (1933) by Ida H. Garrett, only the second book ever written devoted exclusively to this one breed, simply printed in cardstock covers.

3) Pet Library's Chihuahua Guide (1966) by Hilary Harmar, whose primary text on the subject was the much larger "Chihuahua Encyclopedia" (1972).

4) Chihuahuas: A Foyles Handbook (1978) also by Hilary Harmer, an easier condensed verrsion of her most significant "Chihuahua Encyclopedia."