Bibliography:

Grosvenor, M.B. 1960. Wild animals of North America. national geographic Society. Washington.

Seaton, E.T. 1926. Lives of game animals. Doubleday. New York.

Schoonmaker, W.J. 1966. The world of the woodchuck. J.B. Lippincott Co. New York.

Banfield, A.W.F. 1974. The mammals of Canada. University of Toronto Press. Toronto

Encyclopedia Britanica
reference.allrefer.com/encyclopedia/M/muskrat.html -

1981 Missouri Conservation Commission

Chapman, J.A. and G.A. Feldhamer. 1982. Wild mammals of North America. The John Hopkins University
    Press. Baltimore.