16.1 Introduction

Citations are cross-references to bibliographical information outside the current document, such as to publications containing further information on a subject and source information about used quotations. It is certainly not necessary to back everything by a reference, but background information for controversial statements, acknowledgments of other work, and source information for used material should always be given.

The previous chapter showed numerous ways to compile bibliographies and reference lists. They can be prepared manually, if necessary, but usually they are automatically generated from a database containing bibliographic information. This chapter now introduces the many presentation forms of bibliographical sources, and it reviews different traditions regarding how such sources are referred to in a document.

We start the chapter with a short introduction to the major citation schemes in common use. Armed with this knowledge we then plunge into a detailed discussion of how LaTEX supports the different citation schemes. At the time we wrote the first edition of this book, LaTEX basically supported only the “number-only” system. Nearly three decades later, the situation has changed radically. Today, all major citation schemes are well supported by extension packages.

We end this chapter by discussing packages that can deal with multiple bibliographies in one document. This is not difficult if the reference lists are prepared manually or if biblatex together with biber is used, but it poses some challenges if you want to interact with BIBTEX, as well.