LAT 0021: Cicero

Classicists tend to use the Chicago Manual of Style rules for citation, though that depends on what venue the work is intended for--publishers often have their own rules or variations on the standard. Turabian, a derivative of Chicago designed for undergraduate research, is also popular for less formal work.

Classical works are typically referred to by chapter and verse, like Scripture, rather than in conventional footnote/reference style.

Plato Protagoras 309c

Virgil Aeneid 2.250-252

Note: For more formal publication, and if it's relevant to your argument, specify the edition of the work you're using with a full reference/footnote the first time you use it.

List of standard abbreviations (Oxford Classical Dictionary)