Agreed! Though this information mostly arises out of ones own experience in collecting a series! Very often, when looking for a particular mint, moneyer, or denomination, you very quickly get to recognise the varieties that are available as box standard items and, at some point, come to realise 'hang-on, I've only just realised that I've never even seen one of these before, despite the fact it's lumped under S12**A with those other communal garden issues! I've come to learn that very few books are up to speed with rarity! How could they be? Take Withers and BCW, for example, they've opened up the medieval world of coins for everyone, yet you will find unrecorded examples within 20 minutes of collecting within that series. It really only comes down to experience! In all honesty it wouldn't be what it is as a pastime otherwise!