Series number of a journal volume for the rare case where a single journal has multiple volumes with the same volume number.
This element will rarely be used. It handles the case in which a publisher reissues a journal and restarts the volume numbering
with “1”. Duplicate volume numbers would then exist and need to be differentiated in citations. One solution for differentiation
is for the publisher to add a series number to the volume number, and the <volume-series> has been created to hold such a number.
Best Practice: The <volume-series> element should hold the number or name of the series of the
volume’s series (for example, “1” for the original numbering and “2” for the re-numbering), while the <volume> element should hold the number of the volume within that series (for example, “519”).
This element should not be used to capture series information that describes a series of articles within a journal or an issue.