There will probably not really be much by way of external readings for this course, since there is a textbook.

There are other syntax textbooks, and perhaps I’ll name a couple and put short notes here about them, but in general it’s a bit hazardous to consult other textbooks until you are fairly comfortable with syntax. Often other textbooks will approach the same material but formalize it in some other way. You’re responsible for the formalization in class first, and in the Adger textbook, and using a formalization from some other source won’t count as “right” for the purposes of the class.