GERMANY (1986) Ancient & modern opticians*. MUSTER (Specimen) overprint. Scott No B643, Yvert No 1106.
AVAILABLE AT $20
ALLEMAGNE (BERLIN) (1981) Instruments d'optique historiques*. Yvert Nos 602-5. Scott Nos 9NB176-9 surchargés "MUSTER" (Spécimen).
AVAILABLE AT $75
ALLEMAGNE (1981) Instruments d'optique historiques*. Yvert No 922-5. Scott No B583-6 surchargés "MUSTER" (Spécimen).
AVAILABLE AT $75
JAPAN (1986) Electron microscope*. Electron Microscopy Congress issue overprinted MIHON (specimen). Scott No 1701, Yvert No 1594.
AVAILABLE AT $15