The most common method of bibliographic notation in chemical engineering is to put the
author's last name and the year of publication in the sentence where the reference occurs,
using parentheses as needed. For example, you might write the following sentence: “Colburn
and Hougen (1933) first demonstrated how to include the effects of the non-condensable gas in
designing a condenser for a vapor containing a non-condensable gas.” For two authors, include
the last names of both authors; for three use the first author's last name and “, et al.”