In a book-length piece, you should start a new series of notes (i.e. Every time the ideas, facts or opinions of another are used in a piece of work this must be acknowledged with a full reference.
Whether a source is quoted directly or indirectly, paraphrased or summarised, it must be acknowledged with a footnote or endnote. Notes should include the minimum information necessary for a reader to find and consult your source.
Reading it should not be an epic struggle on the part of your hapless reader.
If you decide that a footnote is unavoidable, then the standard procedure is to flag it in the text with a superscript numeral at the point at which it is relevant: I am indebted to Sylvette Vaucluse for kindly providing me with unpublished data from her own research, and to Sylvette Vaucluse and Jacqueline Labéguerie for illuminating discussions of these case studies.
Footnotes at the bottom of the page must be set off in some way from the main text.
The common way of doing this is to put the footnotes in a smaller typeface.
What is your reader supposed to do if she doesn't recognize it — put your book down, go off to the library and find Halliday (1968), and read that book from cover to cover?
You should make every effort to make your work a pleasure to read.
Sadly, countless of students find the thought of writing endnotes and footnotes very challenging and because of this they just prefer to not include them in their papers.
And, it is also due to this why some students obtain lower grades on their dissertations.