Lot 31. Andy Warhol (1928-1987), Skull, signed and dated 'Andy Warhol 77' (on the overlap), acrylic and silkscreen ink on canvas, 15 x 19 1/8in. (38.1 x 48.6cm.). Executed in 1977. Estimate £600,000 – £800,000 ($885,000 - $1,180,000) . Photo: Christie's...