欧美精品久久久久久久自慰,乱色熟女综合一区二区三区,欧美丰满熟妇多毛xxxxx,蜜臀国产在线视频,免费 黄 色 人成 视频 在 线

Peter Drucker. [Photo/Sina Weibo]

Peter Drucker

Born on Nov 19 in 1909, Peter Drucker was described as "founder of the modern management". As a management consultant and educator, he invented the concept known as "management by objectives" and "self-control".