Vancouver
This is the Vancouver style for referencing, used at the Univerity of Portsmouth within the School of Pharmacy and Biomedical Sciences and the Radiography departments.
This guide is modelled on Citing Medicine: The NLM Style Guide for Authors, Editors, and Publishers (2nd edition). You may wish to consult this source directly for additional information or examples.
You can place these where you think they make the most sense. The following guidance does exist:
Numbers should be given to the right of commas and full stops, but to the left of colons or semi-colons. Try to work your sentence so that reference numbers do not come near other numerical data.