99863
Other important work on the subject , both theoretical and experimental , was due to André Blondel , Balthasar van der Pol , Alfred-Marie Liénard , and Philippe Le Corbeiller in the 20th century .
 André Blondel, Balthasar van der Pol, Alfred-Marie Liénard, Philippe Le Corbeiller
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:
 André Blondel, Balthasar van der Pol, Alfred-Marie Liénard, Philippe Le Corbeiller