who's who idiom
（某组织中各人的职位和工作）每人的情况，谁是谁
the people who are most important in a particular group
Who's Who 名人录，人名词典
a book containing information about the world's richest or most famous people
The guest list reads like a Who's Who of top American businessmen. 宾客名单读起来像是美国巨贾豪商的名人录。