Prof Niklaus Wirth (Inventor of Pascal, Modula and Oberon Programming Language) has published two of his Programming Books for free.

Theses books are good to learn about Programming and about Algorithms and Data-Structures in Pascal-ish Languages (Kyan Pascal, Quick or ACTION!)

The books can be downloaded at
http://www.oberon.ethz.ch/books.html

Ciao

Carsten