8 March 2016, bbc.com: The mystery over the @ sign Citat: "...[Giorgio] Stabile discovered a letter sent from Seville to Rome in 1536, which discussed the arrival in Spain of three ships sailing from the New World. It stated that an amphora of wine was sold and "amphora" was replaced with the @ symbol as an abbreviation. Stabile concluded the @ symbol was a common medieval shorthand for units of measure in southern Europe, even if the precise units differed...", backup
8 March 2016, bbc.com: The mystery over the @ sign Citat: "...[Giorgio] Stabile discovered a letter sent from Seville to Rome in 1536, which discussed the arrival in Spain of three ships sailing from the New World. It stated that an amphora of wine was sold and "amphora" was replaced with the @ symbol as an abbreviation. Stabile concluded the @ symbol was a common medieval shorthand for units of measure in southern Europe, even if the precise units differed...", backup