[texhax] Insert text at the beginning of bibliography

[David Vine]

Hello,

I would like to insert some text at the beginning of my bibliography. I 
am using pdfTex with Memoir class and natbib.

Other included packages (not sure if these are relevant): pdftex, 
amsmath, amssymb,  fontencm, textcomp, microtype, mathdots, hyperref and 
memhfixc.

Specifically, I would like to add a couple of lines of text to the 
effect that the Digital Object Identifier (DOI) number included in some 
of the references can be accessed by prefixing "http://dx.doi.org/" to 
the start of the DOI number. I would prefer to not include the full URL 
for each reference.

Any help would be greatly appreciated - thesis submission in a few days 
and this one has me tearing my hair out!

Many thanks,
David Vine