Documentations
C++
Bruce Eckel's Free Online Books Thinking in C++, 2nd ed. Volume 1 Thinking in C++, 2nd ed. Volume 2
Java
Bruce Eckel's Free Online Books Thinking in Java, 1st editionThinking in Java, 2nd editionThinking in Java, 3nd edition
HTML
HTML Documentation The World Wide Web Consortium
MySQL
MySQL Documentation Developer Zone
GIS Software
Basic ArcMap and ArcGIS Documentation Harvard University
PCRaster
PCRaster Documentation Utrecht University