People On Campus
You will be dealing with professors 99% of the time you are on a campus. Professors collect textbooks their entire career and have bookshelves full of old editions they don’t use. Always 1st and 2nd approach professors.
These are the secretaries of the academic departments and most departments have them. They often control the new textbooks coming and going from the department so you should always talk to them BUT talk to them after you have talked to the professors because some admin assistants can act as gate keepers that prevent you from approaching professors.
This is the term we give to anyone who makes large blanket statements such as “no one will be around until 2pm today” or "come back on Wednesday, more people will be here then”. It seems logical and helpful but in reality the best time to find and catch professors is whenever you are passing through the department at that moment. Never base your schedule on professor’s posted office hours or territory experts because you will end up wasting time when you could have found more professors by walking through the department.