Vietcong. 1968, 8th Anniversary of NLF, 30xu+30xu, left sheet margin block of four, contains two horizontal se-tenant pairs, all four stamps have omitted yellow background, usual perforation, no gum as issued, NH, VF, only a part of sheet with this error has been discovered, a common pair is included for comparison, Est. $400-$500 (Image)

Vietcong. 1972, Medicine in Liberated Vietnam, 50xu multicolored, buff color omitted, top sheet margin block of four, no gum as produced, NH, VF and rare multiple, a common stamp is added for comparison, Est. $500-$600 (Image)