A manual for writers of research papers, theses, and dissertations, Ninth edition - Kate L. Turabian 2018

Time and dates
Abbreviations
Style

24.4.1 Time

You may use the abbreviations a.m. (ante meridiem, or before noon) and p.m. (post meridiem, or after noon) in text and elsewhere to designate specific times. The abbreviations should be lowercase and in roman type. Do not combine them with in the morning, in the evening, or o’clock; see also 23.1.5.

24.4.2 Days and Months

In text, spell out and capitalize the names of days of the week and months of the year; see also 23.3.1. In tables, figures, and citations, you may abbreviate them if you do so consistently. (Note that some months in this system are not abbreviated.)

✵ Sun.

✵ Mon.

✵ Tues.

✵ Wed.

✵ Thur.

✵ Fri.

✵ Sat.

✵ Jan.

✵ Feb.

✵ Mar.

✵ Apr.

✵ May

✵ June

✵ July

✵ Aug.

✵ Sept.

✵ Oct.

✵ Nov.

✵ Dec.

24.4.3 Eras

There are various systems for designating eras, all of which use abbreviations with numerical dates. BC and AD are the most common designations, though BCE and CE may be used instead. To refer to the very distant past, a designation such as BP or MYA may become necessary. AD precedes the year number; the other designations follow it (see also 23.2.4 and 23.3.2).