The book Laws of Media was published after McLuhan's death. According to Eric McLuhan this was a big editorial effort. Some tetrads did not make it into the book. In McLuhan Studies Issue 5: The Missing Media Laws there are Tetrads on Unisex, Heterosexual, Homosexuality/Lesbianism, Anaesthesia, Dream and Bed. How the bed flips (reverses) into a trap is interesting alone.