There aren't many books for the oil pastel artist out there. This one and Oil Pastel for the Serious Beginner: Basic Lessons in Becoming a Good Painter are the two that I found recommended again and again when I started using this medium. Both have great information on history, materials, and techniques. The big difference is that this book has examples of many artists' work in it, in a variety of styles, while the Serious Beginner book has only the author's work shown. With only two major books on the medium, you should definitely check them both out.