Those are special skills that no article in the world can transfer to you. Articles and books are for those already knowing the basics from prior first hand experience. In one hand you need to learn and practice compo mechanics and taking impressions (mold making). Then you probably need to finish and match in substance, texture, color, luminosity what you repaired to the surrounding area.
If you really want to learn how to do compo repairs, you need to work along with a good antique picture frame restorer for as long as it takes.
Sorry, I don't know of any better way than this. Having a considerable experience in this field you better believe me when I state that reading books and articles on frame fixing and gilding will only make you an informed speaker (talker) on the subject.
When you become emerged up to your neck into the matter, then you may start reading books and articles and see for yourself how many authors don't even know what they are writing about or how little useful info is written by those who do know.