These guides are the best for the amateur herpetologist or casual naturalist. They are well-organized, with lots of excellent pictures of the various species, life stages, sexes, and variations you are most likely to encounter in the area. Less common species are also pictured. The books feature good information on the habitat, range, and life history of the animals. The books also feature a handy ruler for measuring animals in the field. That is, assuming they will hold still, or you can keep them from wriggling. The books even tell you how to capture and study animals in the field. I have used more technical reference guides and I find myself coming back to these. They are much easier to use, and full of nice pictures. I use these in my classroom for teaching. The Lone Pine guide series is great!