Read Make Em Laugh by Laurence Maslon and Micheal Kantor. This book exams all the great comedians from the 1900 to present. There is a synopsis of all the big acts. There is a good history of both black and white comedans and their influences on each other.  The bad thing is that there is a miss is sequence. For example. Jim Carrey is mentined before Carol Burnette. This may be to the type f comedy. 

It is disappointing that Dana Carvy only gets a mention and not a synopsis like the other comediens because he is one of the best in modern comedy.You will discover something. One the downside;the book is heavy and think. It could be used as a textbook rather than a reading book. There is actually not a lot of reading, so do not buy it. Go to your local library or university mass communication or art department. Those places should have it. There are allusions to many films and comedians you will want to watch Turner Classic Movies or visit Time Life to see if there is something to buy. Will Rogers was and is still the funnest guy in America!