A manual for writers of research papers, theses, and dissertations, 7th edition - Kate L. Turabian 2007

Series
Spelling
Part III. Style 20 spelling

In a series consisting of three or more words, phrases, or clauses with no internal punctuation of their own, separate the elements with commas. Always use a comma before the conjunction that introduces the last item.

The governor wrote his senators, the president, and the vice president.

Attending the conference were Fernandez, Sullivan, and Kendrick.

The public approved, the committee agreed, but the measure failed.

Do not use commas when all the elements in a series are joined by conjunctions.

The palette consisted of blue and green and orange.

If a series of three or more words, phrases, or clauses ends with an expression indicating continuation (and so forth, and so on, and the like, or etc.), punctuate that final expression as though it were the final item in the series. You may, however, add a comma after the continuation expression to prevent confusion after a long series.

They discussed movies, books, plays, and the like until late in the night.

Management can improve not just productivity, but hours, working conditions, training, benefits, and so on, without reducing wages.

Use semicolons to separate the items in a series if one or more includes commas, or if the items are long and complex (see 21.3). If such a series comes before the main verb of a sentence, however, rephrase the sentence.

The three cities that we compare are Hartford, Connecticut; Kalamazoo, Michigan; and Pasadena, California.

but not

Hartford, Connecticut; Kalamazoo, Michigan; and Pasadena, California, are three cities worth comparing.