Is it permissible for a man to have sexual intercourse with his wife while she is in her 'iddah period?

If a man divorces his wife with the first or second pronouncement, she observes her 'iddah in his house because she is still his wife. He is permitted to have intercourse with her if he wishes to take her back. Some scholars stipulate uttering the pronouncement of 'revocation' and having witnesses for it, after which the 'iddah ends, and he may resume intercourse with her. As for the third pronouncement, she does not observe her 'iddah in his house, and she is not lawful for him until she marries another husband. Then, it is permissible for her to return to the first husband with a new contract after the second husband divorces her.