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

Typography of titles
Parenthetical citations–reference list style: the basic form
Part II. Source Citation

Titles of larger entities (books, journals) are printed in italics; titles of smaller entities (chapters, articles) are printed in roman type and not enclosed in quotation marks. Titles of unpublished works (such as dissertations) are printed in roman type and not enclosed in quotation marks, even if they are book length.