World Wide Fund for Nature 1968 - 1983, high-value mint never hinged lot the "forerunner" (by "Groth" listed under F1-F40) with all good sets and souvenir sheets like Mauritius, Swaziland, Gambia and so on. ; in addition to it the Burundi set Michel no. 1596-1608 from 1983 (Michel 1.000.-), Michel total approximate 3.000.-