Guinea Pigs (Complete Pet Owner’s Manual) – this is a great introductory book to guinea pigs and their care. It’s well-written, with beautiful pictures. If you’re a first-time guinea pig owner, this book is a great start.
Super Poopers – Species appropriate nutrition for guinea pigs: A guide to adequate guinea pig food and to reduce your costs – I could be way off the mark, but I imagine the author of this book to be a real earth mother vegan type character. Her book presents an ideal that I’m sure many of us aspire to, but for most of us (particularly city-dwellers), is not entirely achievable.
Even if you don’t have time for a daily forage in the woods for your guinea pigs, this book is still packed full of useful ideas, and has a directory in which you can find almost every plant/fruit/vegetable and check whether it is healthy for your pet. I’d trust this book a lot more than a quick Google search, as I’ve found a lot of incorrect and even downright dangerous advice from just clicking articles which come up on Google.