diff --git a/vignettes/spcosa.Rmd b/vignettes/spcosa.Rmd
index 052b8914fe84564f5953cc20e92bf5b5a4912ef2..2cc671c418b62b59805c02e25d86514f12e3b799 100755
--- a/vignettes/spcosa.Rmd
+++ b/vignettes/spcosa.Rmd
@@ -145,7 +145,7 @@ Although the implemented optimisation algorithms are deterministic in nature, th
 set.seed(314)
 ```
 The **spcosa**-package depends on the **sp**-package (Pebesma & Bivand, 2005) for
-storing spatial information, and the **ggplot2**-package (Wickham, 2009) for visualisation. A basic knowledge of the [**sp**-package](https://cran.r-project.org/package=sp) is highly recommended. Knowledge of the **ggplot2**-package is only needed for fine-tuning **spcosa** graphics. Consult the superb [ggplot2-website](http://docs.ggplot2.org/current/) for details and illustrative examples.
+storing spatial information, and the **ggplot2**-package (Wickham, 2009) for visualisation. A basic knowledge of the [**sp**-package](https://cran.r-project.org/package=sp) is highly recommended. Knowledge of the **ggplot2**-package is only needed for fine-tuning **spcosa** graphics. Consult the superb [ggplot2-website](https://ggplot2.tidyverse.org) for details and illustrative examples.
 
 
 
@@ -681,4 +681,4 @@ sessionInfo()
   Computers & Geosciences 36: 1261-1267 Available online at
   http://dx.doi.org/10.1016/j.cageo.2010.04.005
 
-- Wickham, H (2009). ggplot2: elegant graphics for data analysis. Springer New York (ggplot2.org)
+- Wickham, H (2009). ggplot2: elegant graphics for data analysis. Springer New York