https://www.englisch-hilfen.de/en/exercises/reported_speech/backshift.htm
https://www.englisch-hilfen.de/en/exercises/reported_speech/time_phrases.htm
https://www.englisch-hilfen.de/en/exercises/reported_speech/commands.htm
http://esl.fis.edu/grammar/multi/repspee.htm
http://test-english.com/grammar-points/b1/reported-speech-indirect-speech/
