found: Nelson, J.S. Fishes of the world, c1994:p. 30 (Order Petromyzontiformes (Hyperoartii), Class Cephalaspidomorphi (Monorhina); petromyzontiforms)
found: ITIS, via WWW, June 6, 2003(Order Petromyzontiformes, Subclass Cephalaspidomorpha, Class Cephalaspidomorphi)
found: Catalog of fishes, via WWW, June 6, 2003:classification (Order Petromyzontiformes, Class Cephalaspidomorphi)
found: Encyc. of fishes, 1995:p. 24 (Order Petromyzontiformes - Lampreys. Class Cephalaspidomorphi)
found: Common and sci. names of fishes from the U.S. and Canada, 1991:p. 11 (Order Petromyzontiformes, Class Cephalaspidomorphi--Lampreys)