Ackerly, Spafford C. 1992. Rapid shell closure in the brachiopods Terebratulina retusa and Terebratalia transversa. Journal of the Marine Biological Association of the United Kingdom. Vol. 72, pp. 579-598.
Afzelius, B. A. and Ferraguti, M. 1978. Fine structure of brachiopod spermatozoa. Journal of Ultrastructure Research. Vol. 63(3), pp. 308-315.