Complete Science Pulp

An American science fiction writer. He was honored by fans with three Hugo Awards and by colleagues with one Nebula Award. The Science Fiction Writers of America made him its third SFWA Grand Master and the Horror Writers Association made him one of three inaugural winners of the Bram Stoker Award for Lifetime Achievement.

Contents
Hellhounds of the Cosmos (1932)
Project Mastodon (1955)
The Street That Wasn't There (1941)
The World That Couldn't Be (1958)
Empire (1951)

Hellhounds of the Cosmos (1932)
Weird are the conditions of the interdimensional struggle faced by Dr. White's ninety-nine men.

The Street That Wasn't There (1941)
A disgraced physicist watches his city disappear as people stop believing it exists. Decent SF short story about an invasion of earth in a subtle and unique way.

The World That Couldn't Be (1958)
Like every farmer on every planet, Duncan had to hunt down anything that damaged his crops—even though he was aware this was—The World That Couldn't Be.

Project Mastodon-
A cat-faced alien stranded in Wisconsin befriends locals, then time-engineers portals into prehistoric epochs. The locals start a tourism company for big-game hunters, and maybe a new country: Mastodonia.