Cats vs Dogs research
http://www.diffen.com/difference/Cat_vs_Dog
http://healthypets.mercola.com/sites/healthypets/archive/2010/12/28/reasons-why-cats-make-best-pets.aspx
http://www.cbsnews.com/news/american-heart-association-pets-especially-dogs-are-good-for-the-heart/
http://www.purina.co.uk/content/the-right-pet-for-you/choosing-a-dog/getting-a-new-dog/why-dogs-make-good-pets
http://www.diffen.com/difference/Cat_vs_Dog
http://healthypets.mercola.com/sites/healthypets/archive/2010/12/28/reasons-why-cats-make-best-pets.aspx
http://www.cbsnews.com/news/american-heart-association-pets-especially-dogs-are-good-for-the-heart/
http://www.purina.co.uk/content/the-right-pet-for-you/choosing-a-dog/getting-a-new-dog/why-dogs-make-good-pets