The main primary sources for this topic are not so much textual as visual. For illustrations of the various items of armour, use Snodgrass (1967). You will see frequent references to a poem of Tyrtaios or Tyrtaeus; this can be found in Lattimore's collection of Greek Lyrics, pages 15-16 (library has multiple copies).
Hoplites on an Archaic Athenian Black Figure Column Krater
Hoplite on an Archaic Athenian Black Figure Kylix
*A. Andrewes, The Greek Tyrants (London, 1956) 31-42.
A. M. Snodgrass, "The Hoplite Reform and History" JHS 85 (1965) 110-122.
A. M. Snodgrass, Arms and Armour of the Greeks (Cornell U. P., 1967). Primarily for illustrations.
A. Toynbee, Some Problems of Greek History (Oxford U. P., 1969) pages 250-259.
*J. Salmon, "Political Hoplites?" JHS 97 (1977) 84-101.
P. Cartledge, "Hoplites and Heroes: Sparta's Contribution to the Technique of Ancient Warfare" JHS 97 (1977) 11-27.
H. van Wees, "The Homeric Way of War: the Iliad and the Hoplite Phalanx" Greece & Rome 41 (1994) 1-18 and 132-155. pages 138-148 are especially pertinent.
*T. R. Martin on "The So-called Hoplite Revolution"
What are the different elements which comprise the hoplite panoply and the hoplite phalanx? At what date do the various elements first appear, and at what date are all the disparate parts brought together? How plausibly can the introduction of hoplite tactics be linked to social and political phenomena, in particular the shape of Spartan society and the phenomenon of the tyrant?