Letter form Heleen (the Netherlands) with tree stamps of the set Women issued on 25 March 2013 (and a bonus tulip).
The set of six stamps picture the following women:
-the explorer Alexandrine Tinne (I had previously received this one)
-the writer Belle van Zuylen (top right on the envelope),
-the theologian Anne Zernike (the blue stamp),
-the Utrecht heroine Trijn van Leemput,
-the painter Maria van Oosterwijck,
-and the sovereign Maria van Bourgondië (the red stamp on the envelope).
More information about this issue, and the complete set, here.
See more women on stamps following the links of Sunday Stamps-II.