Barrington, E. J. W., 1936, Proteolytic digestion and the problem of the
pancreas in Lampetra: Proceedings of the Royal Society, London B, v.
121, p. 221-232.
---, 1938, The digestive system of Amphioxus ( Branchiostoma)
lanceolatus: Philosophical Transactions of the Royal Society, London B, v.
228, p. 269-311.
Welsch, U., 1975, The fine structure of the pharynx, cryptopodocytes and
digestive system of amphioxus (Branchiostoma lanceolatum): Symposium of
the Zoological Society, London, v. 36, p. 17-41.