Normalization of a table
Actually, you could go a little further and take the Author out and having a new table named Authors and you could be more rigid and take publication as well.

Book:

Book_num  Book_titl  Author_id  publication edition

200       physics      1        MACGROW      1ST

201       math         2        MACGROW      2ND

204       new java     3        ALPHA        4TH




Author:

Author_id Author_name

   1      john

   2      martin,tina

   3      korth,chira


Still, remember that going full onto normalization has drawbacks on performance as well.

It all depends on the business and how you are trying to manage the data.