...if he can write a book at all, a writer cannot do it by peeping over his shoulder at somebody else, any more than a woman can have a baby by watching some other woman have one. It is a genital process, and all of its stages are intra-abdominal;

No one can tell you what you can and cannot put in your book. So be brave and just write!

Stay within the confines of your chosen topic. If you start to stray away from your topic and find an urge to showcase everything that you know, resist that urge. Remember that you are writing a book, not the book.