I don't know if people are aware of the Eat Your Books website (http://www.eatyourbooks.com)? It's an online searchable index to paper cookbooks — so you can search the content of your own cookbooks, using their search engine.
Their database lists a vast number of cookbooks (over 131,0000, including many of the 5:2 titles, but only around 4,900 of the cookbooks have been indexed (each recipe is entered by hand, so it's a slow process!)
I am one of their 'pro indexers' (I enter recipe details into their database), and their only 5:2 faster 'on staff' I suspect! I've recently indexed two of the 5:2 cookbooks, and I hope to add more in the near future, once I get my hands on copies of the books.
I've just indexed The Fast Diet Recipe Book by Mimi Spencer and Sarah Schenker, and The 5:2 Fasting Cookbook by Angela Dowden.
You can get a free membership, which allows you to add 5 cookbooks from your collection to your EYB Bookshelf, if you want to try it out.