Need some tips on how to read and interpret travel narratives like a historian? Check out the guide put together by Jerry Bentley (University of Hawaii), which includes an annotated bibliography of scholarship on the travel writing genre.
For books about travel writing as a literary genre, include the phrases "travelers' writings" and "history and criticism" in your search.
For books about the travel writing in history, include the phrases "travel writing" and "history" in your search.
The journal literature in history is divided geographically between two major databases: America: History & Life covers journal articles about the United States and Canada, and Historical Abstracts covers journal literature for world history outside the U.S. and Canada, 1450-present. Don't forget that books are the most important publishing format for historians, so don't stop with journal articles in your research!
For journal articles examining travel writing as a literary genre, try MLA International Bibliography.