115901
He studied with Robert Casadesus , Egon Petri , Roger Sessions , and Nadia Boulanger .
 Robert Casadesus, Egon Petri, Roger Sessions, Nadia Boulanger
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Robert Casadesus, Egon Petri, Roger Sessions, Nadia Boulanger