Anatomia Artistica is one of the best book series I’ve found for life drawing references. With thousands of drawings of every portion of human musculature and skeletal structure, this series is an excellent reference for all artists, whether your style is based in realism or caricature.
This book series is “technically” in Spanish. I say technically because the real value of this series is in the hundreds of perfectly rendered artistic templates contained within its pages.
If you wish to start drawing people, but have no idea where to begin, this series might be right for you.
Some of the templates are broken down into basic shapes, which really help you gain understanding of the human form.
Overall, I highly recommend these books.
There are multiple books in the series, however book two has got to be my favorite. However, full disclosure, I only own books 1-3.