Simplify the following text for a Grade 10 native English-speaking person.
Original: He continued to study with many masters of all schools of Tibetan Buddhism , especially His Holiness Dudjom Rinpoche and His Holiness Dilgo Khyentse Rinpoche .
Simplified: He continued to study with many masters , of all schools of Tibetan Buddhism , especially Dudjom Rinpoche , Dilgo Khyentse Rinpoche , and Nyoshul Khenpo Rinpoche .