O 15/AP 00 01" single-ring d.s. (error in date); also 1901 philatelic envelopes from Tientsin with B.R.A. 5c. on ½c. black and green surcharges, both with C.E.F. 3p. pairs " /> cover 1901 (20 Apr.) printed first day envelope from Tongku to Tientsin bearing B.R.A. 5c. (in black) on ½c. tied by circular handstamp and C.E.F. ½a. tied by "F.P.O. N<V>O 15/AP 00 01" single-ring d.s. (error in date); also 1901 philatelic envelopes from Tientsin with B.R.A. 5c. on ½c. black and green surcharges, both with C.E.F. 3p. pairs | Christie's