Datacron Locations

Check if you have the galactic histories (Each are tied to a datacron): http://www.swtor-spy.com/codex/achievement-datacrons/11/

Instructions to find each datacron tied to each galactic history: http://www.swtor-spy.com/datacrons/

The following are empire only datacrons:
1-3
15-22
28-32
48-52

The following are republic only datacrons:
4-14
23-27
53-57
http://www.swtor.com/community/showthread.php?t=315630