References

Textual

1. Bauer, Erika B.; Smuts, B. B. Cooperation and competition during dyadic play in domestic dogs, Canis familiaris, Science Direct, www.sciencedirect.com. Accessed 27 Sept 2007.

2. Bekoff, Marc. Social Play in Coyotes, Wolves, and Dogs, "BioScience," Vol 24, No 4. (Apr, 1974), pp 225-230.

3. Cohn, Jeffry. How Wild Wolves Became Domestic Dogs, "BioScience," Vol 47, No 11. (Dec, 1997), pp 725-728.

4. Jackson, Dorothy W.; Angelino, H.R. Play as Learning, "Theory into Practice," Vol 13, No 4, The Value of Play for Learning. (Oct 1974), pp 317-323.

5. Landsberg, G.M.; Hunthausen, W.L.; Ackerman, L. Handbook of Behavior Problems in the Dog and Cat, 2nd Ed. Elsvier Health Sciences (2004).

6. Scott, J.P. Critical Periods in Behavioral Development, "Science," New Series, Vol 138, No 3544. (Nov 30, 1962), pp 949-958.

7. Spinka, M; Newberry, R.; Bekoff, M. Mammalian Play: Training for the Unexpected, "The Quarterly Review of Biology," Vol 76, No 2. (Jun 2001), pp 141-168.

8. Vila et al. Multiple and Ancient Origins of the Domestic Dog. "Science," New Series, Vol 276, No 5319 (13 Jun 1997), pp 1687-1689.

Visual

a. Black and white dog face. [Online image]. Available http://www.arlgp.org/adopt/dogs/. 26 Sept 2007.

b. Gray wolf. [Online image]. Available http://en.wikipedia.org/wiki/Image:Canis_lupus_laying.jpg. 1 Oct 2007.

c. Phylogenetic tree. Macdonald, D. W. and Sillero-Zubiri, C. The Biology and Conservation of Wild Canids. Oxford UP (2004).

d. Littermates. [Online image]. Available http://commons.wikimedia.org/wiki/Image:Cadelos_palleiros_GFDL1.jpg. 26 Sept 2007.

e. Play bow and submissive roll. [Online image]. Available http://www.dkimages.com. 26 Sept 2007.

f. Beach playbite. [Online image]. Available http://www.ahimsadogtraining.com. 26 Sept 2007.

g. Three dogs playing. [Online image]. Available http://home.earthlink.net/~ejlmp/magginmok.html. 26 Sept 2007.