The Time Machine by HG Wells;
"A Stitch In Time" by John Wyndham;
"By His Bootstraps" by Robert Heinlein;
"The Sorrow Of Odin The Goth" by Poul Anderson.
These happen to comprise two British literary works and two American genre stories.
Wells implies but otherwise avoids the issue of causality paradoxes. The other three works are circular causality stories although the last is set in a causality violation scenario. The four works present a good balance of past, present and future -
Wells: nineteenth century to 702,601 AD, then the furthest future of Earth, and return;
Wyndham: time travel within a character's life time;
Heinlein: twentieth century to far future;
Anderson: twentieth century to the Dark Ages.
The Time Traveler interacts with Morlocks and Eloi. Anderson's Time Patrolman interacts with Goths and Huns. The Time Patrol's mass produced, streamlined, futuristic timecycles are conceptual descendants of the Time Traveller's elaborate nineteenth century contraption. The time traveler sits on, instead of being enclosed by, each of these vehicles. Both Wyndham and Heinlein instead envisage a machine that sends people through time instead of moving past- or future-wards, taking them with it.
