Wanted Wheaties Panels 1935 To 1941

Do you know how folks found cards for their collections in the early 80s? They took out ads in hobby periodicals like John Spalding did in this request for 1935 to 1941 Wheaties Panels in the July 1983 issue of Trader Speaks.

Spalding was also looking to hear from Wheaties collectors for a few research projects and was willing to refund postage costs for info. He passed away in 2012 but was a prominent hobby contributor as a writer, researcher, and collector. 

By the way, the panel included in the ad is from 1936.