Articles in handbooks and annual reviews are usually very good at answering the question "What do we think we know and what needs to be studied?"
They are very good at showing the range of theories and the kinds of methodologies used to study a topic.
Also look at most recent articles on a topic in two particular places: 1) the literature review or introduction at the start of the paper for relevant research already conducted, and; 2) the discussion at the end which usually states what the authors think needs further research.
