Q. what are some authorative websites on "stress management"
One idea is to do a web search limited to government or education sites. For instance, I used Google and did a search like this site:gov "stress management"
Among the results were this page: http://www.nlm.nih.gov/medlineplus/ency/article/001942.htm and this one http://www.nlm.nih.gov/medlineplus/stress.html
Another thought is to search for sites at organizations that have a focus on health matters. For instance, you could try a search on "American Heart Association" "stress management"
Another example "American Psychological Association" "stress management"
A third example "Mayo Clinic" "stress managment"
I hope that's enough to get you started.