There is a wealth of material on the actualism site (I was absolutely stunned when I “discovered” the site) for study. However, it can be helpful to include other views/approaches if they are in line of what is being discussed here.
Two authors come to my mind: Jed McKenna, UG Krishnamurti
Do you recommend other authors or the website is enough for you to study?
The problem with other sources is (and this is something that you will have to confirm for yourself) that Actualism is 180 degrees opposite to the approaches that have been tried so far.
There is no other ism that has proposed the complete eradication of the self in toto.
The general advice would be (at least to begin with) to stick with just Actualism for a while so that it is possible to grasp what it is all about, otherwise there is a risk of it becoming muddled up with other practices. Of it being neither here nor there.
Oh I would recommend this one though - https://www.simpleactualism.com