repeated statements when using for and if

[Yoriz]

There's lots of errors in the formatting of the code you have posted (spaces where they shouldn't be, spaces missing)
There is also undefined variables.
When asking for help please post a minimal code sample that is able to be run.

You could create a variable before the loop book_found = False
Add book_found = True to the end of the if statement
Remove the

elif

statement
After the loop add

if not book_found:
     print ("no books in that interval")