There are many reference charts that include information on civilizations, units, buildings, wonders, and more available for download, with two of the most notable being:
- The Civ4 BtS reference guide (PDF version) BTS v 3.13 by dj_anion
- Complete Civ4 Reference sheets (XLS Version) and (PDF Version) by Michelangelo, Kroym, and Jensen for all versions of Civ4. Compatible to CIV1.74/C4W2.13/BTS3.17