Cross References

One reason for numbering things like figures and equations is to refer the reader to them, as in "See Figure 3 for more details."

Sections, Equations, Tables, etc.

One can generate numbered references to anything for which LaTeX maintains a counter by placing a \label command with some mnemonic name in the appropriate environment. The reference is then generated by use of the \ref command with the same mnemonic.

For example

  \begin{equation}
  \label{eqno1}
    c \geq \sqrt{a^2+b^2+1}
  \end{equation}
  .... intervening text ...
  From Eq.~(\ref{eqno1}) we see ...

Assuming that this is the first equation, the last line will produce "From Eq. (1) we see ..." Note the use of the ~ to ensure that there is no line break between "Eq." and "(1)." Also note that the \ref command produces only the number; if you want the number to be in parentheses (as shown here) you have to include them in your text.

Bibliographic citations

Bibliographic citations work somewhat differently. The following should be consulted: