Spine/covers a bit creased, corners bumped, slight edge wear. Some yellowing. Text is clean and unmarked.
This vintage Ace Double contains the first book publications of Robert Silverberg's The Silent Invaders along with William F. Temple's Battle on Venus.
"Silent Invaders" - A science fiction adventure chronicling the clash of star spies, "Abner Harris came to Earth on a mission of extreme urgency. His orders said that the universe was in dander of enslavement by the pebble-skinned Medlins. And that the fight against their evil scheming called for him to assume the disguise of a flesh-and-blood Earthman. But once in that new synthetic body, he made a mind-numbing discovery: that the real villains of space were his own kind!."
"Battle on Venus" - "George Starkey had to find a way to stop the thousand year war on Venus before his little group of astronauts became early casualties. But where were the headquarters of the contending sides and how do you tell a robot tank that you're neutral. But George had an ally, a Venusian girl who thought stealing was virtuous-and, unknowingly, he had something else that turned out to be the most valuable substance on Venus-a box of chocolate bars!"; 5¾" - 6¾" Tall