International scientific cooperation
IV international Congress on essential oils
- Catalog #
- 3631
- Date of Issue
- 1968 30 May
- Denomination
- 6k
- Color
- Multicolor
- Artist
- Kominarec I.
- Printing method
- Intaglio
- Perforation
- Harrow 11½
- Issued
- 4,000,000
VII World energy conference. WPC
- Catalog #
- 3632
- Date of Issue
- 1968 30 May
- Denomination
- 6k
- Color
- Gold, orange, dark brown
- Artist
- Kominarec I.
- Printing method
- Intaglio
- Perforation
- Harrow 11½
- Issued
- 4,000,000
- Tags
- Moscow
VIII international Congress on mineral processing
- Catalog #
- 3633
- Date of Issue
- 1968 30 May
- Denomination
- 6k
- Color
- Blue, dark blue, green
- Artist
- Kominarec I.
- Printing method
- Intaglio
- Perforation
- Harrow 11½
- Issued
- 4,000,000
- Tags
- St. Petersburg