I will probably get some downvotes for this since I asked a similar question here: CS graduate starting out in graphics design - What are the main principles of design and it was closed down. The answers/comments I had in that question where mostly concerning UI designing which is NOT what I am looking for. The title was a bit deceiving.
I am not a graphics designer at all. I had some primitive skills in Photoshop and a client rang me up through a recommendation from a friend and asked me to produce flyers for his upscale restaurant/bar on a monthly basis. It's a good 700 Euros a month.
I am producing some really nice flyers for him (according to him), however I would like to take the opportunity and learn the professional principles behind this area.
In the linked question, I had an answer that stated I should I read Visual Grammar by Christian LeBorg, which I have just finished.
The other links where mostly concerned with UI design which is not what I am looking for.
What would be a next good book I should read that focuses on flyer design/print media?
I am looking to learn the basic principles behind designing such print media.
I am NOT talking about print requirements(print bleeds, DPI settings etc), I am mostly concerned about "Principles of Design"-style books.
Thanks for all the answers so far, I'm sure most of them are really nice. I can't accept an answer until I have read some of the books here which I plan to do, I have lots of free time on my hands. For now I am reading Universal Principles of Design