Gregg Jefferies #233 Prices, 1989 Topps
Gregg Jefferies Baseball Cards
Gregg Jefferies Trading Cards: Values, Tracking & Hot Deals
Auction Prices Realized Baseball Cards 1990 Leaf Gregg Jefferies
John Racanelli – SABR's Baseball Cards Research Committee
Trouble with the Curve A baseball card hobby blog…
The Shlabotnik Report, Baseball cards, customs and obscure pop culture references
Gregg Jefferies Baseball Cards
Death and Taxes and Baseball Card Litigation [Part II, 1965-1988] – SABR's Baseball Cards Research Committee
1988 Score: A Forgotten Gem - Forums
1990 Topps Baseball #457 Gregg Jefferies New York Mets Official MLB Trading Card (stock photos used) Near Mint or better condition : Collectibles & Fine Art
Why Sports Card Values from the Late-80s and Early-90s Are Low
Is It Worth Grading Junk Wax Baseball, Basketball & Football Cards