A. Wolf 
Key to Exercises in Logic and Scientific Method [PDF ebook] 

Originally published in 1926, this book was written in the first instance for the benefit of those students of Logic and Scientific Method who receive insufficient or no help in the way of oral instruction. The main function of the following pages is to deal with the exercises, as distinguished from the book-questions. It includes chapters on the scope of logic, theory of judgment and immediate inference, and theory of induction.