the four most famous Beijing opera performers specializing in mature male roles during the 1940s, namely [[马连良|馬連良|ma3 lian2 liang2]], [[谭富英|譚富英|tan2 fu4 ying1]], [[杨宝森|楊寶森|yang2 bao3 sen1]], and [[奚啸伯|奚嘯伯|xi1 xiao4 bo2]]