Vancouver (AMA) referencing style

A secondary source/indirect citation is when the ideas of one author are published in another author’s text but you have not read or accessed the original author’s work. Regarding this the AMA Manual of Style says "Authors should always consult the primary source and should never cite a reference that they themselves have not read". Particularly if you are writing an article for publication or a thesis you should adhere to this guidance. If you are writing a less formal document such as an assignment it is always preferable to find and cite the original work, but if that is not possible:

• In the reference list, provide the details of the author of the work in which you found the quotation or idea - the actual source you looked at.
• Make it clear in the text of your document that you are quoting a secondary source.