E book readers and GeoGebra
I paid $8.50 US dollars in 1956 for my calculus text by Thomas. I had that book for years and referred to it often. Now, we have some new possibilities. We can still buy hardbound text books. We can find ebooks which are text books. We can find answers to almost all calculus questions on the internet. We can use GeoGebra to do nearly all of the mathematics involved. We can use a Casio Prizm as a portable device which does much of what GeoGebra can do.
The possibilities are endless- and being continually updated.
So, I have a few observations.
Buy a reader. ( I have the new Kindle with wifi and the Sony PRS-350 pocket reader.)
Store reference books and your textbooks on the reader.
Store instruction manuals for you calculator and for GeoGebra on your reader.
(I have finally begun to use the reference manuals as they were intended.)
Use your reader, with its long battery life as your portable off line reference library.
And finally, when a text book runs from $150.00 to $200.00, argue with the publisher to get a PDF file of that hardbound text free of charge. You should have both the book and the file.