| Subject | Reference |
| Mathematics |
Top 100 Math theorems CuriousMath forum Final Answers (Dr. Michon) |
| HTML |
WDG W3Schools |
| CSS | CSS1-WDG CSS1-W3C |
| Color & Character Codes | Color WebMonkey Char. codes WebMonkey |
| JavaScript | Visiborne Tutorial W3Schools |
| PHP | |
| Java |