Lot Essay
Cf. Rainer Rückert, op. cit. (1966), col. pl. XXX, nos. 1106, 1107 for a pair from the Collection of Dr Ernst Schneider, Düsseldorf. See also Yvonne Hackenbroch, op. cit. (1956), pl. 6, fig. 5. See also the examples sold by Christie's New York on April 1984, lot 201.