Jerry Koosman Baseball Cards
Jerry Koosman Baseball 1969 Season Sports Trading Cards
PSA Magazine: 2022 December #012 by PSA Magazine - Issuu
Leaf – SABR's Baseball Cards Research Committee
Jerry Koosman Baseball Cards
PSA Magazine: 2022 December #012 by PSA Magazine - Issuu
Calaméo - Spring 2022 Auction Catalog
PSA Magazine: 2023 April #016 by PSA Magazine - Issuu
PSA Magazine: 2023 February #014 by PSA Magazine - Issuu
Jerry Koosman Baseball 1969 Season Sports Trading Cards