1. G. Bernier, J.M. Kinet, and R. M. Sachs, 1981 a.The Physiology of Flowering . Vol. I , pp, 27 -28 . CRC Press, Boca Raton, FL. ISBN 0-8493-5709-8.
2. G. Bernier, J.M. Kinet, and R. M. Sachs, 1981 . The Physiology of Flowering . Vol. II , pp.179 -182 . CRC Press, Boca Raton, FL. ISBN 0-8493-5710-3.