Full review on this cover and included notebook. Other notebooks (Stalogy 365 A5, Seven Seas Crossfield, etc.) and paper planners (Hobonichi Cousin) that also fit in this cover, and a few that don't.
A5 size: https://www.amazon.com/Raymay-Multi-Use-Covered-Notebook-Blue/dp/B005JQ0UXM/ref=sr_1_fkmr0_3?ie=UTF8&qid=1470785227&sr=8-3-fkmr0&keywords=raymay+cover
A6 size: http://www.jetpens.com/search?q=raymay+multi+use+cover&v=2
FP Physicist's Review of the A6: https://www.youtube.com/watch?v=n8PFtZb9uIE
