The legendary book.
"I took Wing Chun Do in Hawaii under Kimo Wong for a few years, who was Demile's Student. (Demile himself was one of Bruce's first assistant instructors in his Seattle days.) In early editions of this book, it is Kimo's body flying through the air from Demile's 1 and 3-inch punches. I felt those punches from Kimo, and often trained at his house in private lessons, and have seen clearly what Demile intimates -- his version of this punch, which he passed down to Kimo, was even more refined than Bruce Lee's, involving far less body motion and commitment. The stories of people "flying" from a mere tap that barely moved the puncher's body are completely correct. And Demile and Kimo both got it down even notably better than Bruce.

This art is Bruce Lee's art, refined from Wing Chun by the addition primarily of fencing footwork for more mobility and much aggression, the inclusion of the backfist(a natural for Wing Chun), and a very strong form of sticking hands that classical Wing Chun students can find irritating and overly aggressive which Bruce learned and adapted from his own sifus in Hong Kong, Wong Shun Leung among them..."