The souvenir sheet on the cover is from the "Preserve the Polar Regions and Glaciers" series, released by the Postal service of France on 28 Mar 2009. It is part of about 40 countries to issue stamps on this common theme.
The international stamp campaign is being coordinated by Itella’s Philatelic Centre in Finland. Each country will decide independently on the illustration theme for its issue. A shared feature for the issues is the crystal insigniaI. I regret to inform that Singapore is not one of the participants :(
Below you will find pictures of twenty-eight countries' stamp issues.
Hungary Romania Belgium New Zealand CzechFaroe Islands Estonia Aland Slovenia LithuaniaAndorra Argentina South Africa Switzerland Greenland Croatia Iceland Greece Austria Brazil Australia Japan Canada France Kazakhstan Latvia
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