The World Association for the Development of Philately (WADP) and the Universal Postal Union (UPU) jointly conceived and developed the WADP Numbering System - WNS, which was launched on 1 January 2002.

EE021.07

Country / Post Estonia
Date of Issue 9 August 2007
Primary theme Economy & Industry
Energy (Hydro)
Subject Estonian Mills - Hellenurme Water Mill
Width 35.5 mm
Height 25.5 mm
Denomination 5.50 EEK
Number in set 1
Layout/Format sheet of 10
Perforations 13.5 by 13.5
Stamp issuing authority Estonian Post
Printer AS VABA MAA Tallinn
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