New links: "Related Links"

I have added some links related to nature, such as the page of Nature or the page of PubMed, with great articles related to apes (see example in the section Related Links). Apart from that I have included a link to Zoos Worldwide, which does not just includes zoos but also sanctuaries and wildlife parks.
The link to National Geographic deserves a special comment, have a look at their extraordinary photo gallery, for instance this instance with baby animals, and look for the animal you want in their fast "animals A-Z" browser, for instance, this is some information about chimpanzees, mountain gorilas, lowland gorilas or sifakas.
Don't hesitate visiting Greenpeace's page either.
I hope you like these new links! I will be looking forward to adding your new ones!