In honor of the vast amounts of white stuff now covering my neck of the woods, some images of horse books in the snow. It's not a common theme, actually; summer (or California) is the standard backdrop.
Winter Pony by Jean Slaughter Doty (Nothing like starting with the obvious.)
Horses Across The Ages, Jeanne Mellin author and illustrator
Happily After All by Laura C. Stevenson
Panky In The Saddle by Nancy Saxon
The Ponies Of Mykillengi by Lonzo Anderson