Specific Rules #3 for Edition (required) to Citing Conference Proceedings Vancouver Style: First editions

If a proceedings does not carry any statement of edition, assume it is the first or only edition.

Use 1st ed. only when you know that subsequent editions have been published and you wish to cite the earlier one.

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Citing Medicine: The NLM Style Guide for Authors, Editors, and Publishers [Internet]. 2nd edition. Chapter 3: Conference Publications