This is the Old Man's War Series: 6-Book Collection Set: Old Man's War, The Ghost Brigades, The Last Colony, Zoe's Tale, The Human Division, The End of All Things, by John Scalzi book set, includes: 

Old Man's War ISBN: 9780765315243 

The Ghost Brigades: An Old Man's War Novel ISBN: 9781250359551 

The Last Colony: An Old Man's War Novel ISBN: 9781250359537 

Zoe's Tale: An Old Man's War Novel ISBN: 9781250359520 

The Human Division: An Old Man's War Novel ISBN: 9781250359544 

The End of All Things: An Old Man's War Novel ISBN: 9781250359568

Brief Description:
A stunning novel of the long war for human survival--in a universe replete with hostility

Marc Notes:
A Tom Doherty Associates book.;A Tor paperback--P. [4] of cover.;Hugo Award Finalist.

Review Quotes:

"Though a lot of SF writers are more or less efficiently continuing the tradition of Robert A. Heinlein, Scalzi's astonishingly proficient first novel reads like an original work by the late grand master...This virtuoso debut pays tribute to SF's past while showing that well-worn tropes still can have real zip when they're approached with ingenuity." --Publishers Weekly (starred review)

"Solid...[Scalzi] sidesteps most of the cliches of military science fiction, delivers fast-paced scenes of combat and pays attention to the science underpinning his premise." -- San Francisco Chronicle

"Thought-provoking!" -- Entertainment Weekly

"Smartly conceived and thoroughly entertaining, Old Man's War is a splendid novel." -- Cleveland Plain Dealer

"Gripping and surpassingly original. It's Starship Troopers without the lectures. It's The Forever War with better sex. It's funny, it's sad, and it's true." -- Cory Doctorow