Caponizing is removing the testes, it would render them sterile. It is performed when they are still quite small (young) the complications on a grown roo are exponetially higher, and if they are already crowing likely will not stop the crowing. If there is any "slip" even the tiniest piece of one of the testes that is accidentally left in they will still crow and may or may not be sterile, but will still act like full roo.
Sorry I can't help w/ any articles or knowledge of surgical "de crowing" I never even knew it was possible.