Today I have been editing a medical-type research paper. To check the references, I consulted PubMed. PubMed is fantastic; nearlly all the medical references are listed on it and it's free. This is very helpful if you only need to check spellings, or look for the correct volume and page numbers. There are also links to full articles, if these are freely available.
PubMed is available through http://www.ncbi.nlm.nih.gov/
PubMed is available through http://www.ncbi.nlm.nih.gov/