MALI (1983) Lavoisier*. Laboratory apparatus*. Formula for water*. Trial color proof pair. Bicentenary of Lavoisier's Water Analysis. Scott No 476, Yvert No 475.
AVAILABLE AT $40
FRANCE (1955) Chardonnet*. Microscope*. Trial color proof strip of 5. Invention of rayon. Scott No 762, Yvert No 1017.
AVAILABLE AT $80
RWANDA (1972) Chemist in laboratory. Set of 8 color separations. Scott No 492. Fight against racism..
AVAILABLE AT $75
RWANDA (1975) Chemist in laboratory. Set of 6 color separations. Scott No 678. 10th anniversary of Rwanda National University.
AVAILABLE AT $75