"You can move backward by mining it’s bibliography (or references). You can move forward by using Web of Science to do a cited reference search. And you can move side to side (sort of) by reading it with an eye both for content and for vocabulary that you can use when constructing future searches."
"to search thoroughly ...
1. Select the fewest, most essential keywords that represent your topic.
2. Then, gather synonyms for those keywords.
3. Try a variety of searches using different combinations of keywords and their synonyms until you are no longer noticing relevant articles crop up that you've not already seen."