The Cochrane Library is a database of systematic reviews and protocols (review criteria) which is free in the Island of Ireland because the Health Research Board partially funds it. It is named after and builds upon the ethos of Dr. Archie Cochrane who was a prisoner of War (POW) in the second word war, and in order to keep people alive in the concentration camp he was in, started a rigorous written account of what was working and not working to keep them alive. This began "his life-long work in respiratory medicine, epidemiology & health services research"
Did you know that The Cochrane Library is included in an Eolas search? Only abstracts though. We are working to get full text added.
A literature review is just a review of what is written by academics about a topic . There are different types of literature reviews, and certain types suit certain disciplines. A literature review is traditionally chapter 2 in a Masters Thesis.
In a traditional narrative literature review you search a discovery tool like Eolas, Web of Science, Google Scholar and find studies. You do not have to state where you found the literature, or what criteria you used to include or exclude a study.
A systematic review is considered to be rather impartial and less biased because there are strict rules (protocols) that you need to publish and then adhere to when performing your searches. So you might have to say that you are going to search x,y and z databases, and you might even have to say what search terms or headings you are going to use in advance. A systematic review is used to find out truth if "Different clinical studies give different answers." ( Glasziou 2011)