Repeated citations of the same source may use a shortened form in the footnote.
You may use the author's last name and the page number in most cases.
Kreider, 23.
If there are multiple resources by the same author, use the author's last name and an abbreviated form of the title plus page numbers.
Kreider, Patient Ferment, 19.
Kreider, Journey Towards Holiness, 15.
In the past, it was the practice to use "Ibid." for repeated citations. This remains acceptable, but the preferred style is the short form.