Soft corals:

"Soft Corals and Seafans" by Fabricius and Alderslade (2001)

 

  Most underrated general hobby book of the last century:

 
"The Living Aquarium" Crescent Publishing (1981)

*  includes DIY glass, acrylic, fiberglass and epoxy-wood aquariums

 

  Beginners Marine Aquarium - General:

"The Conscientious Marine Aquarist" by Robert Fenner, TFH/Microcosm (1998)

* perhaps THE best book on general marine keeping if you'll commit to a good and proper read

"The Marine Aquarium" by Dick Mills, Tetra (1987)

* a dated reference but still gets very high marks. A favorite for its unique layout.

"The New Marine Aquarium" by Michael Paletta (1999)

* a short, easy, digestible read that is a must-have, first book for new aquarists

 

  Reefkeeping:

"Aquarium Corals" (2001) by Eric Borneman, the go to book for aquarium corals

"The Reef Aquarium" series by Delbeek and Sprung

* valuable and comprehensive tomes!

"Natural Reef Aquariums" by John Tullock (1997)

 

  Classics:

"The Marine Aquarium Reference: Systems and Invertebrates" by Martin Moe, Jr. (1993)

* a book of immeasurable impact on the hobby in the earliest years

"The Marine Aquarium Handbook: Beginner to Breeder" by Martin Moe Jr. (1992)

* this book changed the path of the aquarium hobby perhaps more than any other work of its kind. Must-have.

"The Reef Tank Owner's Manual" by John Tullock 

* a pioneer in the reef hobby in the US

Texts written by Steve Spotte

* technical but pioneering references

 

  Systems and Hardware:

"Aquatic Systems Engineering: Devices and How They Work" by P. Escobal (2000)

* very technical to read, but an amazing wealth of information here.