What is the topic of Dylan Mandel's previous research?
 Dylan Mandel's previous research is on Tlingit syntax, specifically "The What, When, and Why of Sá – a Probe into the Alaskan Tlingit Interrogative."
What is the topic of Dylan Mandel's previous research? ->:  Dylan Mandel's previous research is on Tlingit syntax, specifically "The What, When, and Why of Sá – a Probe into the Alaskan Tlingit Interrogative."