The Cobra in the Dream & Casonetto's Last Song

[El Santo]

Does anyone have a clue when these stories, published posthumously in 1968 and 1973 respectively, were actually written?  I have them in Beyond the Borders, and those Baen collections from the 90's (unlike the more recent ones from Del Rey) don't include any handy essays laying out the chronology of the included tales.

[elegos7]

They were probably written in 1929, Casonetto perhaps a year later.