In the Oxford style the citations in the text normally consist of a raised (superscript) number and a list of footnotes at the bottom of the page for all citations on that page.
Footnote with complete bibliographic information
It is not always necessary to have a reference list at the end of an essay when footnotes contain the full bibliographic information.
Consult your teacher for guidance.
1 Alan Bryman. Social research methods. 3. ed. Oxford: Oxford university press, 2008, 65
Footnote with abridged bibliographic information
If a document or source is cited several times in the text, you can use abridged bibliographic information (author´s family name, title and page number(s) or equivalent). This is combined with a reference list at the end of the essay.
2 Bryman. Social research methods, 79
Footnote when two references in a row are from the same source
Use “ibid.” (=same as last entry) when two references in a row are from the same source and state page number(s) if different (and applicable).