SF in the Harry Harrison/Poul Anderson vein?
Oh, my; that is a river. I read that as adventure stories with ideas and wonder.
Second to MOTE IN GOD'S EYE. Plus Niven and Pournelle's OATH OF FEALTY.
DESCENT OF ANANSI. FALLEN ANGELS is free at the BAEN free library. (If you haven't just download the whole Free Library.)
S.M. Stirling: CONQUISTADOR, ISLAND IN THE SEA OF TIME (and sequels)
F.M. Busby: RISSA KERGUELEN, DEMU TRILOGY
Larry Niven: THE INTEGRAL TREES, THE SMOKE RING (especially the latter)
Keith Laumer: Retief! (free)
David Drake: Lt. Leary, Commanding (Never mind Leary: Mundy rocks!) (free)
Eric Flint: 1632, 1633 (free)
David Weber: On Basilisk Station, Mutineer's Moon (free)
Philip Jose Farmer: The Green Odyssey, Two Hawks from Earth, The Maker of Universes (Not sure all are available in ebook but if you like Harrison's DEATHWORLD...)