A manual for writers of research papers, theses, and dissertations, Ninth edition - Kate L. Turabian 2018
Periods
Punctuation
Style
21.1 Periods
21.2 Commas
21.2.1 Independent Clauses
21.2.2 Series
21.2.3 Nonrestrictive Clauses and Phrases
21.2.4 Other Uses
21.3 Semicolons
21.4 Colons
21.5 Question Marks
21.6 Exclamation Points
21.7 Hyphens and Dashes
21.7.1 Hyphens
21.7.2 Dashes
21.7.3 Multiple Dashes
21.8 Parentheses and Brackets
21.8.1 Parentheses
21.8.2 Brackets
21.9 Slashes
21.10 Quotation Marks
21.11 Apostrophes
21.12 Multiple Punctuation Marks
21.12.1 Omission of Punctuation Marks
21.12.2 Order of Punctuation Marks
This chapter offers general guidelines for punctuation in the text of your paper. Some rules are clear-cut but others are not, so you often have to depend on sound judgment and a good ear.
Special elements such as abbreviations, quotations, and source citations have their own guidelines for punctuation, which are treated in relevant chapters in this book.
If you are writing a thesis or dissertation, your department or university may have specific requirements for punctuation, which are usually available from the office of theses and dissertations. If you are writing a class paper, your instructor may also ask you to follow certain principles for punctuation. Review these requirements before you prepare your paper. They take precedence over the guidelines suggested here. For style guides in various disciplines, see the bibliography.
21.1 Periods
A period ends a sentence that is a declarative statement, an imperative statement, or an indirect question. A period can also end a sentence fragment, if the context makes its rhetorical function clear, but this usage is rare in academic writing. In all these cases, the period is a terminal period and, between sentences, should be followed by a single space.
Consider the advantages of this method.
The question was whether these differences could be reconciled.
Put a period at the end of items in a vertical list only if the items are complete sentences (see 23.4.2). Otherwise, omit terminal periods, even for the last item, and do not capitalize the first words.
The report covers three areas:
1. 1. the securities markets
2. 2. the securities industry
3. 3. the securities industry in the economy
Individual periods can also be used in other contexts, including abbreviations (see especially 24.1.3) and citations (16.1.2 and 18.1.2), and also in URLs (20.4.2), where they are often called dots. Strings of periods, or dots, can be used in quotations (see 25.3.2), where they are called ellipses, and in tables (26.2.6) and front matter pages (A.2.1), where they are called leaders.
Do not use periods after chapter and part titles and most subheadings (see A.2.2) or after table titles (26.2.2). For periods in figure captions, see 26.3.2.