1. Anoxygenic phototrophic bacteria (APB) are good model organisms used to study the origin and evolution of life, photosynthesis and nitrogen fixation mechanism.

2. Bergey's Manual of Systematic Bacteriology: Volume One : The Archaea and the Deeply Branching and Phototrophic Bacteria (Bergey's Manual of Systematic Bacteriology (Springer-Verlag)) George M

3. Cyanobacteria the blue-green bacteria (formerly called blue-green algae), a subgroup of the kingdom Procaryotae, unicellular or filamentous phototrophic organisms that use water as an electron donor and produce oxygen in the presence of light