68400
He studied with Guillaume Geefs at the Brussels Académie Royale des Beaux-Arts and was the friend of Peter Ludwig Kühnen ( de ) ( 1812 – 1877 ) , a painter originating from Aachen , specialised in painting romantic landscapes .
 Guillaume Geefs, Brussels Académie Royale des Beaux-Arts, Aachen
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Guillaume Geefs, Brussels Académie Royale des Beaux-Arts, Aachen