fixed typo

vignettes/spcosa.Rmd

@@ -203,7 +203,7 @@ In estimating the spatial mean, differences in surface area of the strata are ta
 ```{r}
 estimate("standard error", stratification, sampling_pattern, my_data)
 ```
-The spatial cumulative distribution function (SCDF) (see deGruijter _et al._, 2006) can be estimated by means of
+The spatial cumulative distribution function (SCDF) (see de Gruijter _et al._, 2006) can be estimated by means of
 ```{r}
 scdf <- estimate("scdf", stratification, sampling_pattern, my_data)
 ```