3 Cross-references

Cross-references make it easier for your readers to find and link to elements in your book.

3.1 Chapters and sub-chapters

There are two steps to cross-reference any heading:

1. Label the heading: # Hello world {#nice-label}.
   • Leave the label off if you like the automated heading generated based on your heading title: for example, # Hello world = # Hello world {#hello-world}.
   • To label an un-numbered heading, use: # Hello world {-#nice-label} or {# Hello world .unnumbered}.
2. Next, reference the labeled heading anywhere in the text using \@ref(nice-label); for example, please see Chapter 3.
   • If you prefer text as the link instead of a numbered reference use: any text you want can go here.

3.2 Captioned figures and tables

Figures and tables with captions can also be cross-referenced from elsewhere in your book using \@ref(fig:chunk-label) and \@ref(tab:chunk-label), respectively.

See Figure 3.1.

par(mar = c(4, 4, .1, .1))
plot(pressure, type = 'b', pch = 19)

Figure 3.1: Here is a nice figure!

Don’t miss Table 3.1.

knitr::kable(
  head(pressure, 10), caption = 'Here is a nice table!',
  booktabs = TRUE
)

Table 3.1: Here is a nice table!

temperature	pressure
0	0.0002
20	0.0012
40	0.0060
60	0.0300
80	0.0900
100	0.2700
120	0.7500
140	1.8500
160	4.2000
180	8.8000