Sometimes when reading a book or journal article, you may come across a summary in which the author has made reference to or quoted from another work. Even though you have not read this “second” work, you may wish to refer to it. This is called secondary referencing.
It is always best to try to locate the original work and quote from it, but sometimes this is not possible. When this happens you must make clear in your text both the source you are quoting from and the original source, but it is the one you have actually looked at that appears in your reference list.
The Vancouver style does not give specific direction on secondary referencing; the following is adapted from practice in other referencing styles.
Format of in-text citation
Author of the quote (Year, "cited by" Author of resource you have seen, superscript of reference number from list)
Examples of in-text citation
Armstrong (2006, cited by Kanwal1) reports that 1.3% of the population is infected….
Dalan & Leow (2007, cited in Propranolol [DrugDex]2) states that the incidence of cardiorespiratory arrest is rare….
Reference List [Only include a reference for the resource that you have actually seen.]
1. Kanwal F, Schnitzler MS, Bacon BR, Hoang T, Buchanan PM, Asch SM. Quality of care in patients with chronic hepatitis C virus infection: a cohort study.
Ann Intern Med. 2010 Aug 17;153(4):231-9. [The Armstrong article appears in the references of this article]
2. Propranolol. In DrugDex [database on the Internet. Greenwood Village, CO: Thomson Micromedex. Updated periodically. [cited 2010 Aug 31]. Available from:
http://www.thomsonhc.com/home/dispatch [The Dalan and Leow article appears in the References for this monograph.]