Ernst Wildi's book has a very technical approach and I found it hard to read. The quality of the pictures featured is quite disappointing. This book deals almost exclusively with Hasselblad cameras, so you'd better look elsewhere to learn how to use your Yashica TLR.
Roger Hicks' and Frances Schultz's book is a very good introduction to MF and LF photography and is easily available new. You could also try to get "Medium-Format Handbook: A Guide to Rollfilm Photography", Roger Hicks' previous book on the subject (ISBN: 0713716576), which is available used trough Amazon.com. This one also includes some funny pictures of a younger Roger.
Theodore Disante's book is the second best choice, but it is not available new and is quite hard to find used. "Medium Format Cameras" by Peter Williams (ISBN: 1584280425) offers a similar approach as Disante's book, is available new, but the general quality of the book is poorer IMHO. It features a few pages on the Yashica TLRs.