Ceratophyllum demersum Robert H. Mohlenbrock USDA-NRCS PLANTS Database / USDA NRCS. 1995. Northeast wetland flora: Field office guide to plant species. Northeast National Technical Center, Chester. - Not copyrighted image	Ceratophyllum demersum Robert H. Mohlenbrock USDA-NRCS PLANTS Database / USDA NRCS. 1995. Northeast wetland flora: Field office guide to plant species. Northeast National Technical Center, Chester. - Not copyrighted image	Ceratophyllum demersum USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. Vol. 2: 75.
Ceratophyllum submersum Jan Kops et al. - Flora Batava - Permission granted to use under GFDL by Kurt Stueber. Source: www.biolib.de - Permission is granted to copy, distribute and/or modify this image under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".