We may now have a definite date for the design of Rudolf Schrötter's
In the 1962 exhibition catalogue "Lisovane Sklo" at UPM, Prague in 1962, was a vase described as "four-sided vase with raised, oval lens to each side. Design date 1955, Rosice." Catalogue number 125.
A second piece of information has given the pattern number for these, Rosice pattern number 914/150 and 914/200.
Accordingly, Sklo Union: Some Views has been up-dated.
This has come as a surprise as conventional wisdom suggested a circa 1940 date-line. One still has to treat contemporary sources with caution.