Amman, Jost, 1539-1591. Kunstbüchlein. Pictorial archive of decorative Renaissance woodcuts. New York :
Dover,  c1968
“Revised republication, incorporating all 293 illustrations, of the work originally published by Dover in 1968 under the title 293 Renaissance woodcuts for artists and illustrators, which was … republication of Jost Amman’s Kunstbüchl[e]in.”–T.p. verso.
ISBN 0486219879 (pbk.)
Beatie, Russel H., 1915- Saddles ; foreword by Dean Kratel ; drawings by Nancy Kay Niles and by Judy Osburn. Norman : University of Oklahoma Press, 1981.
ISBN 080611584X : $35.00 (There is likely a later and more expensive edition ($70.00))
N.b. Beatie’s scholastic value has been called into question, so keep this in mind, and keep the Morton’s handy.
Country life book of saddlery and equipment. Also known as: The Howell book of saddlery and tack / consultant editor, Elwyn Hartley Edwards. New York : Howell Book House, 1988.
Reprint. Originally published: The Country life book of saddlery and equipment. London ; New York : Country Life Books, 1981.
Fair Lady Aside. Unknown author, etc.
Informative work on the history of the Side Saddle.
Liedtke, Walter A. The royal horse and rider: painting, sculpture, and horsemanship, 1500-1800. [New York?] : Abaris Books in association with the Metropolitan Museum of Art, 1989.
Newkirk, Tim. Celtic Warriors. London : Blandford, 1986.
(Page 69 has a photo of a pair of iron Welsh Stirrups, dated late 10th Cent that were found in Glamorgan. Currently the property of the National Museum of Wales).
Steffen, Randy, 1917- The horse soldier, 1776-1943, by Randy Steffen ; ill. by Randy Steffen. Norman : University of Oklahoma Press, 1976-.
v. 1. The Revolution, the War of 1812, the early frontier, 1776-1850. – v. 2. The frontier, the Mexican War, the Civil War, the Indian wars, 1851-1880. – v. 3. The last of the Indian wars, the Spanish-American War, the Brink of the Great War, 1881-1916. – v. 4. World War I, the Peacetime army, World War II, 1917-1943.
Steffen, Randy, 1917- Horsemen through civilization. Colorado Springs : Western Horseman, 1967.
This book reprints material originally published in the Western Horseman.
Steffen, Randy, 1917- United States military saddles, 1812-1943. Illus. by Randy Steffen. Norman : University of Oklahoma Press, 
Vernam, Glenn R. Man on horseback. New York : Harper and Row, 1964.