Explorateur de timbres ↺ Scott or Y & T ? Chinese Inventions 1999 Lithographed by The House of Questa, UK. Perf. 13¾. Regular Stamps (December 20, 1999) Sheet size 5x5. Sc 915 / YT 894A Sc 916 / YT 894B Sc 917 / YT 894C Sc 918 / YT 894D Souvenir Sheet (December 20, 1999) Sc 918a / YT —