Reference to information that is retrievable is appropriately made in the reference list. This information includes but is not limited to articles published in scholarly or mass-circulation print or electronic journals, magazines, or newspapers; books; studies and abstracts presented at professional meetings; theses; films, videos, audio, and other multimedia; package inserts or a manufacturer’s documentation; monographs; reports from government agencies or working groups; databases and websites; blogs; legal cases; patents; and news releases.
References should be listed in numerical order at the end of the manuscript (except as specified in 3.3, References Given in Text, and 3.5, Numbering). Two references should not be combined under a single reference number.
References to material not yet accepted for publication or to personal communications (oral, written, or email) are not acceptable as listed references and instead should be included parenthetically in the text (see 3.3, References Given in Text; 3.15, Electronic References; and 3.13.9, Special Materials, Meeting Presentations and Other Unpublished Material). According to the Council of Science Editors, “Many publishers do not permit placing any form of unpublished material in the end references”8(p639); the reason for this is because these references typically are not retrievable.