I remember years ago finding a searchable archive, I think of some sort of Italian-American institution, which claimed to have every 78 ever released in Italy in its collection, but Google has failed me.
These label discographies are most useful at the labels themselves, so I'll move them there. I wish the Linden discography would offer more dates. The company must have advertised in the local Seattle papers. If anyone has access to the Seattle Times archives, please check.
I've added this Ellington discography as "Ellingtonia Discography" to the entry for Duke Ellington, where we already have a link to the Duke Ellington Panorama discography