Creative Illustration is the best of the Loomis books, although they are all excellent. I began discussing the Figure Drawing book last night because it related to the question that had been asked. If I could have only one of his books this is the one I would choose.
Other books have similar information on figure drawing to the Loomis book on the subject. But this book "Creative Illustration is unique. The information in this book is pretty singular. Written in a time when there were illustrations in a ll of the magazines, this book was aimed at young artists who needed the particular set of skills necessary to make it into that trade. Much of what they needed to know then, is the same as what artists need to know today .
Loomis lays out his principles in clear drawings and his explanations are easy to follow. Above is a difficult concept made readily understandable. I like that his books are "simple". There is a place for dense tomes that require careful study, but the basic ideas a young artist needs to know should be gained first from easily aproachable material. The illustration above for instance shows the same scene in a number if different keys, and it can be understood at a glance.
Above is a drawing explaining the steps of difference in different intensities of light. I referred a reader of this blog to this chart some time ago. Again I don't know where else I have seen this concept well explained.
Here Loomis explains ways to generate thumbnails for a painting. Some of the pictures in the book are dated, but most of the ideas are timeless. Creative Illustration is long out of print and the copies that are available bring a high price generally. Evidently they occasionally come up on
EBay, and sell for more a reasonable sum. You can read them online though, here.
You could save them to a disk and take them to a printer if you don't like reading on a screen.