Well, first, since this is English you should not capitalize the first "Famous". If one is writing about only one author's lunch, than, yes, it is author's lunch. However, if one is writing about several famous authors' lunches, than both would be plural resulting in authors' lunches.
who are the famous authors in belgium
Famous is an adjective; authors is a plural noun.
Stephen and Tabitha King , Book Authors
Nien Cheng is one and a famous poet is Bei Dao.
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names of different authors in management
Florida is home to many famous authors. Some of those authors include Piers Anthony who writes Science Fiction Books, and romance author Heather Graham.
if you guys want to know this you have to be famous
John Updike is a famous author. He wrote the book Rabbit, Run.
Madagascarn Liam
Homer and Hesiod.
Tolstoy