https://books.google.com/ is another option to look into. I tried searching there for your example of "Waiters on the Dance" and it appears there is no ebook version at present. Calibre is another option to use for searching out ebooks. It has an ebook search feature built into the program. When you use it you get a response back of where a given book is available as an ebook (if it is) and at what price the book is being offered. Since the book came out in 1972 and the author is still alive it's a sure bet that it wouldn't be offered at a site like Gutenberg of course. The author is only 66 yrs old and still quite alive. Open Library is another possible place to look but I can't say if they will have the book as an ebook either. Google seems to say that there is no ebook version period.