This is a beautiful souvenir sheet, issued by Guinea in 2007, honoring the father of the atomic bomb physicist Robert Oppenheimer. Also featured on the sheet are Nobel Prize winning physicist Albert Einstein, the STEREO spacecraft, mathematician & physicist Henri Poincaré, the father of modern physics Galileo Galilei, and a brief written biography of Oppenheimer. The sheet is Michel catalog #5311/Bl.1475, and is Post Office fresh, mint never hinged, and F/VF.