Occasionally, you will run across a work that has neither a personal nor corporate author. In that case you can use a few identifying words from the title of the source, which are placed in the author position in the entry in the reference list.
There are as yet few employment opportunities in the field of Martian anthropology ("Martian Anthropology" 1986:569).
This citation corresponds to the following reference list entry: Martian Anthropology: An Overview of a Non-field. 1986 Encyclopedia of the Inner Planets. Abridged. Space City L-5:L-5 Publishing Matrix.