Progress in Electronics Series of 1973 Block of Stamps

GUGLIELMO MARCONI 1874-1937 INVENTOR OF WIRELESS TELEGRAPHY Art Craft OFFICIAL FIRST DAY OF ISSUE MARCONI SPARK GAP MARCONI SPARK COIL Progress in Electronics YORK, JUL 10 1973 NY SERIES OF 1973 J.S. Lindsay 4314 Nelson Dr. Peoria Tel. Marconi Spark Coil Marconi Spark Gap Progress in Electronics Marconi Spark Coil 6c Marconi Spark FIRST DAY OF ISSUE Marconi Spark Coil Gap 6c Marconi Marconi Spark Coil Spark Gap Progress in Electronics Progress in Electronics 6c TMarconi, Spark Gap 6c Progress in Electronics