Josef Albers : Glass, Colour and Light.

Guggenheim Museum. 1994

Catalogue

32. Skyscaper 11
1929
Sandblasted flashed glass 36.2 x 36.2cm.

30. Skyscraper 1
1927/1929
Sandblasted opaque flashed glass 34.9 x 34.9cm.

28. City
1928
Sandblasted opaque flashed glass with black paint, 33 x 55.3cm.
Badley damaged with sections of glass missing.
Alber's numerical notations in white chalk or pencil are visible on the surface.

21. Frontal
1927
Sandblasted opaque flashed glass with black paint, 34.8 x 47.9cm.

https://ia800808.us.archive.org/9/items/glascoli00albe/glascoli00albe.pdf