Books like The Foundations of Singing
Franklyn Kelsey
The Foundations of Singing is 117 pages, about 2 hours 9 minutes at 250 words a minute.
7 books to read next
How long each takes
Ganamrutha Varna Malika 2.2 h 
The Diagnosis & Correction of Vocal Faults 3.9 h The Voice of the Mind 6.7 h 
Training Tenor Voices 3.2 h 
Singing for Dummies 6.8 h 
Basics of Vocal Pedagogy 5.7 h 
Complete Handbook of Voice Training 4.7 h Bar height shows length. Estimated at 250 words a minute.