Achilles, the maintenance manuals are published by Pw up in Canada, they cover 4 or 6 very thick binders - probably not what you want. Operationally, aircraft systems manuals go into adequate depth. If you have a particular question, I may be able to help, being familiar with the -20, -27/28, -65b, -67d. Otherwise I'm at a loss where you might be able to find a general treatise on reverse flow free turbines.