.General post office imperforate proof, 40 sen in light yellowish green (instead of bluegreen), full printing sheet of 400 stamps with horizontal and vertical gutter pairs including a bridge block, only known sheet in this colour without numbers and letters in margins and written inscriptions Gezien 28/11 1952 and fiat tjitak 1/12 '52. both with signature, unknown colour in Zonnebloem and Prangko, an unique sheet!
