Here in Kansas we have many types of pears floating around. Here is 500+ Hard to find apple or pear? Check Kansas
Here is a database with thousands more “pomologie” Question the History of a pear or know some history? Post it here! - #74 by clarkinks
Communis Europe would be a good section to look in. Here is some of the sub categories LESCRETS FRUITS ET POMOLOGIE LISTE des variétés de poires existantes .
Nick botner was growing 500 pears Nick Botner’s place is For Sale! | Seattle Tree Fruit Society
Preservation of varities was taken over by this group Botner – Temperate Orchard Conservancy
This site is great reference Chathamapples pear information - it's worth reading as the author has an extensive knowledge of pears
Please also see the pears of new york digital version The Project Gutenberg eBook of The Pears of New York, by U. P. Hedrick.
Here is the latest nurseries list we have
These are common types of winter, summer and asian pears Varieties – Pear | WSU Tree Fruit | Washington State University