196? 50B blue  A zecea aniversaire a miscarii mondiale pentru pace 50B blue  Traiasca Pacea si prietenia intre popoare
1966 International Solidarity Fund I 5L blue
1973 ISF II  No wmk 3L blue 5L red brown
1980  ISF III  (same motives)  wmk RPR 3L olive 5L red brown
1987  ISF IV  (same motives)  no wmk 3L ultramarine 5L red brown

There is no difference in description of ISF 1973 5L and 1987 5L - does anybody know how to tell them apart?