I'd appreciate references to that effect, please.
Good god... I wouldn't know where to start. It's everywhere. Take a look at Lam Kam Chuen's "The Way of Power", as one example, and note that his references to the classical instructions and admonitions are also common to almost all other Chinese martial arts AND to many of the sayings in Aikido. Particularly, IIRC, comments about the 8 powers, etc., that are also mentioned by O-Sensei. It's all the same basic stuff, Lee.