Netherlands 1967 - 夏季切手、価値表記なしの誤印、4枚連結のブロック - NVPH 880f

From the Netherlands, the Zomerzegel, with a printing error and without denomination inscription, in a block of four, is postfranked with original gum and a clipping mark in the sheet margin, NVPH 880f, from 1967, with a Konink Wording certificate from the Nederlandsche Keuringsdienst stating Postfris with original gum and no defects (certificate dated 04-11-2014) and catalog value €3,400 (NVPH 2023).