Two photos signed by winners of the Nobel Prize in Chemistry: a glossy 5 x 7 photo of Vladimir Prelog, noted for his research into the stereochemistry of organic molecules and reactions, signed in black ink, "V. Prelog"; and a matte-finish 4.5 x 6.5 photo of George Porter, known for his study of 'extremely fast chemical reactions, effected by disturbing the equilibrium by means of very short pulses of energy,' signed and inscribed in the lower border in blue ink. In overall fine condition. Accompanied by the original mailing envelope for the Prelog.