Is there a guide to engines?

I’d like to be able to identify engines but it seems that as I think I learn one, I see one just like it (to me) and it has a different number. Is there a good book that I can really study to be able to better identify and learn them?

For steam, here is a website with a listing of the Whyte System of engine classification: http://www.steamlocomotive.com/misc/wheels.shtml I don’t know much about diseasals so I can’t help you out there. [:D]

Search Walthers site for a book called “Field Guide to Modern Diesel Locomotives” published by Kalmbach. It’s a difinitive book for all diesel locomotives.