I found this book several years ago and boy did I love it!
The book is a collection of lesson dealing with various subjects such as basic drawing, perspective, shading etc.
While I cannot really say tht one would learn to draw in 30 days, but this book is actually really fun to work with. I've done the program twice already and after the last time I've decided tio go over it every six month.
It's time to start again. The goal is to draw every single day and perfect my drawing skills. Already setting the date for the next year's session.