I'm looking for something to help me understand pools, and the new Ada 2012 sub-pools. I've seen the rationale example and the example at Adapower but I find they're somewhat lacking in giving you a good understanding of what's going on.
Absent knowledge of a definitive text or particular use-case, here are a few resources:
§13.4 Storage Pool Management, Ada 95 Rationale.
§6.4 Access types and storage pools, Ada 2012 Rationale.
§13.11.6 Storage Subpool Example, Ada 2012 Reference Manual.
Memory Management with Storage Pools, AdaPower.
Arena storage pool, RosettaCode.
Gem #77: Where did my memory go?, AdaCore.