(386a) 1921 5,000k dark green and pale blue, Madonna and Child, center inverted, l.h., well centered, faint horizontal crease in bottom margin, otherwise v.f., with clear 1964 BPA, plus 2002 Philatelic Foundation certificates. A beautiful stamp. One of the premier Inverted Centers of 20th century Europe, less than 100 examples reported (used and unused), of which at least 38 are tied up in museums, cat. $16,000