Candlewick Press 2003
We have most of the "ology" books and they're pretty fun. Dragonology was our first one and was a favorite with Madeleine for quite a while. It's all fiction, of course, but presented like a lost journal of discovery. There's even an alphabet of Dragonology that Madeleine memorized and used to write letters to her friends (or secret notes to herself that she didn't want anyone else to read).
We even ended up buying the Dragonology board game. It's fun to play because there are tiny Dragon hunter figures and you have to collect the dragons by traveling all over the map. The winner gets to record their name and date in the provided antique looking record. This ups the competitive nature of the game because everyone wants to have their name written down for posterity! (Plus it's been really fun to get the game out and see when we last played it).