Well... surprise, surprise, surprise... it looks to be one of those impossible search tasks. I've had several offblog discussions with people about textbooks online, and it seems to be fraught with copyright issues. Textbook publishers are (I guess I should have expected this) VERY cautious about putting their materials online. I don't know if it's a worry about liability, fear of copyright infringement or what.. but the truth is that few textbooks have their entire text online.
You might think that going to Google Books would solve the problem--aren't they there? Well, yes, there are a few--but only ones that are pre-1923 (the current copyright cutoff date). Since most of the concepts of interest are relatively recent (post 1955), these pre-1923 texts aren't much help.
Since I was failing at my searches, I turned to the "Ask A Librarian" feature at the Library of Congress. This is a fantastic feature that lets you send an email to a reference librarian with a question that they might hope to answer. (I have to say that the good people at the LOC deserve every bit of credit they get for offering this service. They're amazingly good!)
In this particular case, I just forwarded my question to them, and got back the following answer: