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

Punctuation
Notes-bibliography style: the basic form
Part II. Source Citation

In notes, separate most elements with commas; in bibliography entries, separate them with periods. In notes, enclose facts of publication in parentheses; in bibliography entries, do not. The styles are different because a note is intended to be read like text, where any period would signal the end of a citation. Bibliographies are designed as lists in which each source has its own entry, so periods can be used without confusion to separate the elements of author, title, and publication data.