What PCGS Research Reveals About Coins as an Alternative Asset: Correlation, Returns, and Wealth History
https://varimail.com/articles/how-a-simple-grade-move-turned-a-kid-into-a-serious-coin-steward/
How PCGS Data Shows Graded Coins Behaved Differently Than Stocks and Bonds PCGS' market data and price guides have tracked coin values across decades