1. Fortpflanzungsbiologie, Entwicklungszyklen und vergleichende Frähenwicklung acoeler Turbellarien;Apelt;Mar. Biol.,1969
2. Normal embryonic stages of the squid Loligo pealii;Arnold;Biol. Bull.,1965
3. Cephalopods;Arnold,1971
4. Relationships and phylogeny of the Turbellaria;Ax,1963
5. The Phylogenetic System: The Systematization of Organisms on the Basis of Their Phylogenies;Ax,1987