Comparative/Superlative

http://esl.fis.edu/grammar/rules/comp.htm

http://www.english-the-easy-way.com/Adjectives/Formation_SuperLative_Adjectives.htm

http://www.elfnet.com/tutorials/adjcompsup.php

http://www.learn-english-today.com/lessons/lesson_contents/adjectives-ex.html

http://www.eslbase.com/grammar/comparative-superlative