To understand Sparta and its role in ancient Hellas, one should become well acquainted with ancient sources. Here, I have listed ancient writers and documents one should peruse.

Aristophanes' Lysistrata

Euripides' Andromache

Herodotos--His discussion of Sparta's prominent position in the Peloponnese

Pausanias on Lakonia

Pausanias on Messenia

Plutarch's Life of Lykourgos

Plutarch's Life of Lysander

Plutarch's Life of Agis

Plutarch's Life of Kleomenes

Plutarch's Life of Agesilaos

Thucydides' Histories

Xenophon's Agesilaos

Xenophon's Anabasis

Xenophon's Constitution of the Lakedaimonians

Xenophon's Hellenika