Cloudsley-Thompson, J.L.  1999.  The Diversity of Amphibians and Reptiles:  An Introduction.
    Springer-Verlag.  Berlin, Germany.

Gordon, Malcom. & Olson, Everett.  1995.  Invasions of the land.  Columbia University Press.
    New York, New York.

Graham, Jeffrey.  1997.  Air-Breathing Fishes:  Evolution, Diversity, and Adaptation.  Academic
    Press.  San Diego.

Schmalhausen, Ivan Ivanovich.  1968.  The Origin of Terrestrial Vertebrates.  Academic Press.
    New York, New York.

Lemon, Roy R.  1993.  Vanished Worlds:  An Introduction to Historical Geology.  Wm. C. Brown
    Publishers.  Dubuque, Iowa.

Source for anatomical comparison pictures
All "" picture obtained from the Yahoo Image Gallery