1. D. C. York, “The Photosynthetic Bacteria,” ed. by R. K. Clayton and W. R. Sistrom, Plenum Press, New York, N.Y., 1978, p. 657.
2. F. Gobel, “The Photosynthetic Bacteria,” ed. by R. K. Clayton and W. R. Sistrom, Plenum Press, New York, N.Y., 1978, p. 907.