1964 Sc 2899-2901. Big chemistry – for a national economy. Scott 2872-2874

1964. Big chemistry – for a national economy
Catalog numbers: Scott 2872-2874, Standard Collection 2899-2901, Michel 2872-2874, Yvert 2797-2799.
Perforation: comb 12 x 12½
Color: Multicolor.
Printing: Offset lithography.
Print run: 4,000,000.