Complete Fugue Lessons by Marcel Dupré is a theory method in two volumes. Focusing on the Fugues, this first book presents the whole method to conceive a Fugue with some exercises. All the answers are available in the second volume of this series.
Really helpful for Organ players, this book will interest any musician who is interested by the Fugue. Marcel Dupré (1186-1971) was an organist and a composer. He is well-known for his review of the work of J.S. Bach.