"Closed islands of the sky.  The air is not free.  Trespassers will be prosecuted."  From The Children's Newspaper, 1934.

From We Want To Know by Craig, Burke & Babcock, 1940.

From Amrita Bazar Patrika, 1961.

"How high is the sky?"  From the Bombay Sunday Chronicle, 1947.

From Park College's 1948 yearbook.

"Illimitable spaces of barren land under a cold Alaskan sky."  From Shadowland, 1922.

"Don't buy blue sky!"  From The Film Daily, 1926.

"None of life's strings can last."  From Park College's 1973 yearbook.

"The sky reflects back to us some fundamental questions about the nature of the world and our role in it" (The Great Canoes in the Sky: Starlore and Astronomy of the South Pacific). 

From Tulane's 1970 yearbook.

The sky is red?  We did some digging, and it's true!  The Sky Isn't Blue (Janice Lee).  

From The Sky is Red by Jean Milner, 1935.

A pairing of quotations:

"You are the sky.  Everything else—it's just the weather."
—Pema Chödrön

"This world is made of clouds and of the shadows of clouds.  It is made of mental landscapes, porous as air, where men and women are as trees walking, and as reeds shaken by the wind."
—John Cowper Powys, Wolf Solent