The Ubilla-Echevez collection of gold coins of the world - Christensen, Henry; Christensen, Henry ([editor no identificado], 1964)
"Including a magnificent group of extraordinarily rare; eight, four, two and one escudos struck in Lima and México; two and one escudos struck in Cuzco and Santa Fe de Bogotá; from the late 1600's and early 1700's, many of these have been unknown to numismatists"--A la cabeza de la portada: Public and mail auction sale--Función de compilador determinada por el catalogador