Book Cover Design: Non-Fiction Literature Analysis

A catalyst, in case you don't know, is an event or person that incites the protagonist and/or antagonist into action.
A hardbound sometimes uses a cover jacket that includes a cover wrap of a few millimetres where the front cover image wraps over onto the front flap.
Once the final proofread manuscript has been typeset (called the typescript), and the book extent (number of pages) is finalised and the kind of paper has been selected, the spine width can be calculated. Each publishing house have their own formula to calculate the spine width. Amazon KDP has an online spine width calculator that you can use if you are publishing through them, see https://kdp.amazon.com/cover-calculator. Please send me the template if you are using Amazon KDP. If you are not publishing with Amazon KDP, please ask your publisher the spine width once you get to that stage of the production process.