Lest Darkness Fall by L. Sprague de Camp which appears to recently have received a reprinting, my copy is from the 40s. Deathworld by Harry Harrison. I've been

Lest Darkness Fall by L. Sprague de Camp which appears to recently have received a reprinting, my copy is from the 40s. Deathworld by Harry Harrison. I've been waiting for some screenplay writer to stumble across this one, and if I had to guess James Cameron probably did, but just didn't tell anyone. SLAN by A. E. van Vogt. The Witches of Karres by James H. Schmitz. Lord Kalvan of Otherwhen, and Paratime by H. Beam Piper. However the best of all, is maybe only slightly less know, since the author is certainly extremely well known: Tuf Voyaging by George R. R. Martin. An absolutely fantastic collection of stories about an ecological engineer.