http://www.englishexercises.org/makeagame/viewgame.asp?id=3634
http://www.ego4u.com/en/cram-up/grammar/relative-clauses/exercises?02
http://www.ego4u.com/en/cram-up/grammar/relative-clauses/exercises?03
http://www.ego4u.com/en/cram-up/grammar/relative-clauses/exercises?05
http://www.ego4u.com/en/cram-up/grammar/relative-clauses/exercises?06
http://www.ego4u.com/en/cram-up/grammar/relative-clauses/exercises?07
http://www.ego4u.com/en/cram-up/grammar/relative-clauses/exercises?08
http://www.ego4u.com/en/cram-up/grammar/relative-clauses/exercises?09
http://www.ego4u.com/en/cram-up/grammar/relative-clauses/exercises?10
http://www.englishexercises.org/makeagame/viewgame.asp?id=1255
http://www.englisch-hilfen.de/en/exercises/pronouns/relative_pronouns.htm
http://www.englisch-hilfen.de/en/exercises/pronouns/relative_pronouns2.htm
http://www.ego4u.com/en/cram-up/tests/relative-clauses-1
http://www.ego4u.com/en/cram-up/tests/relative-clauses-2
http://www.ego4u.com/en/cram-up/tests/relative-clauses-3