Manuscripts and books from those whose shoulders we stand on.
Sound Transmission in Sea Water
by M. Ewing, L. Worzel, A. Vine, and A. Woodcock. 1942
This book was one of the first Navy references in underwater sound, and it is still has historic perspective and relevence today. Sound Transmission in Sea Water was furnished to the US Navy in 1942 for personnel involved in design, instruction, operation, and understanding of underwater sound equipment and data. Also, included is the (recommended) Joe Worzel autobiograpy (pdf) explaining the exploits of getting this data during WWII.
Mechanics of Underwater Noise
by Donald Ross, 1976
Mechanics of Underwater Noise was written by Donald Ross in the summer of 1976. It has been used as a reference text in many university and commercial courses ever since. It seems somehow to have become THE book on its subject, and even today it is still readily available on Amazon.com and here.
Principles of Underwater Sound
by Robert Urick, 1983 (third edition)
Principles of Underwater Sound is a classic book on the subject. Despite being one of the first books, it's still a key reference with large parts of the material unavailable elsewhere. Behind the engineering treatment is clearly a solid understanding of the science behind things.