Pencil signature on promissory note to strive to become a war officer, September 17, 1943.

Hans "Specker" Grünberg (July 8, 1917 – January 16, 1998) was a German military aviator who served in the Luftwaffe during World War II. As a fighter ace, he was credited with 82 aerial victories claimed in approximately 550 combat missions. The majority of his victories were claimed over the Eastern Front, with 21 claims over the Western Front, including five flying the Messerschmitt Me 262 jet fighter.