The book is available at Project Gutenberg (I have not checked for other online sources). There's also a free audiobook at LibriVox!
(Two Medicine Lake; photo in the book)
Table of Contents
Two Medicine
Hugh Monroe
The Woman Who Earned a Man’s Name
The Story of the Thunder Medicine
Pu-nak′-ik-si (Cutbank)
How Mountain Chief Found His Horses
White Fur and His Beaver Clan
The Story of the Bad Wife
Old Man and the Woman
Ki-nuk′-si Is-si-sak′-ta (Little River)
Old Man and the Wolves
New Robe, the Rescuer
Puht-o-muk-si-kim-iks (the Lakes Inside): St. Mary’s Lakes
The Story of the First Horses
One Horn, Shamer of Crows
The Elk Medicine Ceremony
Na-wak′-o-sis (the Story of Tobacco)
Iks-i′-kwo-yi-a-tuk-tai (Swift Current River)
The Jealous Women
Ni-na Us-tak-wi (Chief Mountain)
The Wise Man