Both of these methods require that all entries in the reference list must be cited in the text. The author-year method cites all references using the last name of the author and the date published. Follow the instructions for authors published by your journal for this format. There are many variations in citation style. APA requires alphabetical order.
Some disciplines still prefer the traditional footnote.
If placed at the end of the chapter they are called Notes to Chapter 1 and are included in the Table of Contents as subheads. Because of the increasing use of microfilming and electronic processing methods for theses, placement of footnotes at the bottom of the page is preferred. Begin numbering with note 1 in each chapter whether the notes are at the bottom of the page or at the end of each chapter.