First published in the early 50's. Tight, clean, flat books. Spines and edges with wear; wrappers and spines with creases. Pages toned. Edges stained. Some curling. 

HELLFLOWER

"Once He had Been a Star Master—Now He Dealt in Soul-Shattering Ruin..."

Farradyne had committed the one unpardonable error a Space Master could make. He didn't die along with the other 32 passengers when his ship smashed into the Bog on Venus.

They broke him—exiled him to the rotting fungus fields of Venus.

Now his only desire in existence was to return to the cool, gleaming sea of deep space.

And there was a way—only one. But he would have to become the vilest parasite in the universe—peddler of a poison that stripped the spirit, before it consumed the body...."

The Complete Venus Equilateral

Collects:

• QRM - Interplanetary (1942)
• Calling the Empress (1943)
• Recoil (1943)
• Lost Art (1943)
• Off the Beam (1944)
• The Long Way (1944)
• Beam Pirate (1944)
• Firing Line (1944)
• Special Delivery (1945)
• Pandora's Millions (1945)
• Mad Holiday (1947)
• The External Triangle (1973)
• Identity (1945)

This is definitely classic hard science fiction from the 1940's. The technology is the focus of the stories, and the heroes are engineers and scientists. The book explores the effects of technology on society, as all good sci-fi does. In this book, a space station has been established at a LaGrange Point between Venus and the Sun, to improve communications between Venus, Earth, and Mars. The station is threatened at times by space pirates, conniving businessmen and politicians, etc. and the engineers on board the station figure out technological solutions to save the day. 

Highways in Hiding

It was infinitely worse when everyone in the world insisted it couldn't have happened the way he knew it had.

In a world where ESP and telepathy were normal, it was difficult to keep secrets. But Steve's search for his missing sweetheart brought him to the threshold of one of the greatest secrets of all time. And it was obvious that somebody would stop at nothing to keep him from uncovering it.

What were the oddly sinister symbols along otherwise ordinary roads? What was behind the spreading plague called Mekstrom's Disease? Why were there "blank" spots where telepathy didn't work? Who was the elusive enemy with powers even beyond those ESP had bestowed on mankind?

And, most important of all . . . could Steve find that enemy before they made him vanish too?

And then it came to him that what he really wanted was to possess a body of Mekstrom Flesh, to be a physical superman. . . .