It happens ...

[csziggy]

6. Write a canned response

To the effect that without sufficient information you cannot provide the proper answer.

Or an ultra-complete response that include the entire syllabus, schedule, reading lists, test schedule and any other details you can shove into it for every single class you teach (or if you want to be really cruel, every class that semester in your department). Then let them sort it out.

If they are incapable of looking this stuff up, they may not be college material.

I finished college in the pre-internet days when you had to go to the first class to get this information or go look at a notice posted on the professor's door. The college was very cheap on copying so the professors were limited in how much they could print and give out. Most professors wrote the reading list on the blackboard for the students to copy while listening to them explain the course requirements and what they expected from the students.

The other way we could find out what books might be needed was to go to the college bookstore where the professors were supposed to have arranged for the books to be in stock. But if your professor did not adhere to the standard list for that course, you could end up spend lots of money on books he didn't use.