What is the minimum temperature difference that can be detected by the
touch of the human hand? For example, if you touch two identical
objects, one with the left hand and one with the right hand, how much
difference in temperature between the two objects must there be to for
you to say that one is warmer than the other? The temperature range
that I'm specifically interested in is 30-35C. I'd also like a
citation of where the information came from so that I can quote it as
a reference. Thanks

You won't be much good at detecting temperature differences bwteeen your hands
unless you swap the objects over during the test.

http://www.sofweb.vic.edu.au/science/famsci/activity/middleyr/biology/bmy22.htm

I can tell when a room goes below 18C or above 29C (but only in the
evening!) and I think you'd be doing well to get much detection of a
small range.

The thing that initialy popped into my head was "a change of 3
degrees". I can't recall where I would have learned that though, so I
wouldn't put much stock in it.

Human's normal blood temperature is between 36-38, depending on the person.
Although I did not find what changes in temperature a human cal feel,
I did find out that there are different levels of receptiveness:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15362149&query_hl=14

It's probably not realy what you were looking for but I hope it helps.

Here's and interesting abstract on extended cold exposere if you are interested: 
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16125855&query_hl=2