Germany 1923 20pf E.EL.P. (Mi. IV) Overprint on Rhein-Main Flight Card w/Certificate

Rhein-Main flight postcard, franked with 5pf Germania and 20pf blackish-red-orange on light greyish-yellow, overprinted “E.EL.P.” (Eleonore-Ernst Ludwig Preis), each tied by “Flugpost Rhein u. am. Main / Frankfurt / (MAIN) / 23.6.12.” c.d.s., to Darmstadt, the 20pf adhesive with corner crease at lower right, else a lovely example of this scarce usage, with 2014 Jaschke-Lantelme certificate. (Mi. IV, €2,000)