Reference works are called collective works in the AMA Manual of Style. Here are its directives for citation:
collective work: A publication, such as an anthology or encyclopedia or other collection, in which a number of contributions are assembled into a collec-tive whole. There are 2 types of authorship in a collective work: (1) author-ship of the collective work as a whole, which may include revisions, editing, compilation, and similar authorship that went into putting the work into final form, and (2) authorship of the individual contributions (see 5.6, Intellectual Property: Ownership, Access, Rights, and Management).
Christiansen SL, American Medical Association, Iverson C. AMA MANUAL OF STYLE, 11th EDITION. Vol 11th edition. Oxford University Press; 2020. Accessed August 19, 2020. https://search-ebscohost-com.proxy.lib.csus.edu/login.aspx?direct=true&db=nlebk&AN=2363704
Example
Degner LF, McWilliams ME. Challenges in conducting cross-national nursing research. In: Fitzpatrick JJ, Stevenson JS, Polis NS, eds. Nursing Research and its Utilization: International State of the Science. New York, NY: Springer; 1994:211-215.
