1. N. Pfennig; H. G. Trüper and N. Pfennig, “The Photosynthetic Bacteria,” ed. by R. K. Clayton and W. R. Sistrom, Plenum Press, New York, 1978, pp. 3–18 and 19–27.
2. J. F. Talling, “Physiology and Biochemistry of Algae,” ed. by R. A. Lewin, Academic Press Inc., New York, 1962, pp. 741–757.
3. “Illustrations of the Japanese Fresh-Water Algae.” ed. by H. Hirose and T. Yamagishi, Uchidarokakuho Publishing Co., Ltd., Tokyo, 1977.
4. “Bergey’s Manual of Determinative Bacteriology,” 8th Ed., ed. by R. E. Buchanan & N. E. Gibbons, The Williams & Wilkins Company, Baltimore, 1974.