Training materials
Authors: Hadley Wickham
and Contributors: Derek Wright or Gildas Le Corguillé or Hadley Wickham or Nene Barry or Sergio Martínez Cuesta or Stéphanie Robin
Authors: Hadley Wickham
and Contributors: Derek Wright or Gildas Le Corguillé or Hadley Wickham or Nene Barry or Sergio Martínez Cuesta or Stéphanie Robin