At last Ken leveled off in the troposphere, at an altitude of five miles.
"Fly By Night"
Arthur Dekker Savage
Troposcatter Propagation via the troposphere.
"The Dawn of Amateur Radio in the U.K. and Greece A Personal View"
Norman F. Joly
Below us the troposphere, divided into five levels, each of seven thousand feet, teemed with the life of the air.
"Astounding Stories of Super-Science July 1930"
Various