Storm Over Warlock: A Science Fiction, Post-1930 Classic By Andre Norton! AAA+++

Stranded on the alien world of Warlock, Shann Lantree's expedition camp has been wiped out by the Throgs, beings so alien that humans have yet to communicate with them. Lantree must quickly learn how to survive under harsh conditions while being chased by the Throgs -- and how to distinguish the real from the dreamed when he meets the mysterious Wyverns.