Additional details of the day's events are not entirely certain—Robey gave three different accounts later—but he began to contact both stamp dealers and journalists, to tell them of his find. After a week that included visits from postal inspectors who tried to buy it back, and the hiding of the sheet under his mattress, Robey sold the sheet to noted Philadelphia dealer Eugene Klein for $15,000. Klein placed an advertisement on the first page of the May 25, 1918 "Mekeel’s Weekly Stamp News" offering to sell copies of the invert ($250 for fully perforated examples, $175 for stamps with one straight edge), but announced in his following week’s ad that the entire sheet had been purchased by an individual collector. The buyer, who paid $20,000, was "Colonel" H. R. Green, son of Hetty Green.