The Greks Bring Gifts was originally published in 1964 and reprinted in paperback in 1968 (the cover above). It is a classic science fiction tale of apparently benevolent aliens who turn out to be not so.
Murray Leinster (pseudonym of William F. Jenkins) was a prolific early science fiction writer with literally hundreds of stories, articles, radio plays, television scripts, and other works. He published his first story in 1916 and his last novel in 1969. He also wrote other genre fiction during the heyday of the pulps and would use variations of William Jenkins if a magazine already had one of his stories under the Leinster name!
His stories include one of the first mentions of a universal translator ("First Contact" 1945) and one of the first descriptions of a computer ("A Logic Called Joe" 1946). He also won a Hugo award for his novelette "Exploration Team" in 1956.
Greks is available on Biblio for as little as $3.97, including shipping.
From the back of The Greks Bring Gifts: They came to Earth in their space ship, bearing fabulous gifts - such as machines that did any day job automatically, and fertilizer that made plants shoot up overnight. But they presented their gifts with contempt, and with a look in their eyes that made people feel "creepy". 

Still, because of the brave new world they promised, they Greks could be forgiven anything - until they left and people discovered the machines were breaking down. Then their only choice was to beg the Greks to come back, on their own terms. And they knew the terms would be hard...

The Long Way Home was originally published as a serial novel with the title No World of Their Own in the magazine Astounding in 1955. It was printed in book form in 1978 with the return of some parts that had been edited out of the serial version by Tor.
The story revolves around a crew of four humans who had embarked on an experimental hyperspace-drive equipped spaceship for a one year mission. They find many planets and aliens in their journey and even add one alien to the crew - the feline-looking humanoid on the cover. However, upon their return they find that the premise of the drive was false and that 5000 years have passed since their departure.
Most of the novel concentrates on the crew and the alien, Saris, and how they manage to unwind a cold war between Earth and its Centauri colonies (with aliens of their own) and the oppressive rule of a computer known as the Technon. There is a significant part of the story told from the alien perspective of Saris making it one of the first with that kind of plot line.
It was written over half a century ago. Despite that it still has over 160 ratings on Goodreads. It does get poor marks, generally, for the characters; with the caveat that Anderson's characters usually have more depth. It does get high marks for premise and plot and the science, though not perfect, has a lot of elements that are still believable (or actual) in the current state.
​Overall it is a recommended hard science fiction read from the "classic" era. It can be snatched up on Biblio for as little as $3.97 including shipping.