Dr. Shigo is the Father of Modern Arborculture...that in itself is an inside Shigoism...lol! He, like George Carlin, were very much concerned with language. Heal/seal is only one example. I remember hearing a rather light talk and a follow up article where he was making a point to use 'arborculture' instead of 'arboriculture'. Most people never use the 'i' anyway...his example...parliament. I dropped the 'i' a long time ago and a few of my nerdy arbo buddies catch the reference and the in-joke.
I don't have any links for his work. My bookshelves are full and most of his books are there. My suggestion is to take a breath and go down the Google rabbit hole and follow your whims. If you decide you want ot buy any of his books get hold of me first. I'm purging. There have been threads here about purging tools, magazines and books. None of them are easy. I'd really like to find good homes for all of my surplus goodies.