Basing on Bardon's book as reference, I think that Kuji In books will interest you, as it is more initiatory system rather than grimoire or ways to do more of a magic.Interested in books like the ones they've written, like master key system, initation into hermetics, etc... I'm not that into grimoires or spells.
Jason Augustus Newcombe - 21st Century Mage
Jason Miller - Real Sorcery