The companion and handbook genre is a publication type that has flourished in the last decade. The goal is for leading scholars to provide a thorough description of the subject matter of a field while also giving the most current interpretations of key questions. Each essay in a companion reflects an important subject facet and identifies the books and articles which are crucial for a greater understanding. Companions for history include:
Blackwell Companions - 276 records (including both print and online versions)
Oxford Handbooks - 189 records (including both print and online versions)
Literature reviews are a particularly useful resource when doing research. They address the issues involved in a particular question and the debates among scholars. They map out the intellectual terrain succinctly and give you the major landmarks in terms of key authors and significant titles for greater understanding. It is one of the best places to find discussion of issues that are unresolved or in contention.
Miguel Cabrera, Casta painting of a Mexican family, ca 1763 ("From male Spaniard and female Amerindian, Mestiza") (Wikimedia Commons)