Relative Pronouns

http://www.englisch-hilfen.de/en/exercises/pronouns/relative_pronouns2.htm

http://www.englisch-hilfen.de/en/exercises/pronouns/relative_pronouns.htm

http://www.englishexercises.org/makeagame/viewgame.asp?id=1255

http://www.english-4u.de/relative_pronouns_ex1.htm

http://speakspeak.com/english-grammar-exercises/intermediate/relative-pronouns-who-which-that-whose-when-where

http://grammar.ccc.commnet.edu/grammar/quizzes/which_quiz.htm

http://www.usingenglish.com/quizzes/234.html