I got out some old textbooks to help Colin figure out how to make a jetpack, and I only found three.
1.) Elementary Differential Equations
2.) A Second Course in Elementary Differential Equations
3.) Differential Equations with Applications and Historical Notes
Which is funny in and of itself, but not quite as funny as finding some bloke's phone number written in one, and in another a fancy nameplate was printed, and the name "Gorilla Pain" was written in rather fancy calligraphy.
Apparently, I pulled in DiffEQ class.