https://cipotato.org/genebankcip/wp-content/uploads/sites/3/2017/06/A-Morphometric-Study-of-Species-Boundaries-of-the-Wild-Potato-Solanum-Series-Piurana-Solanaceae-and-Putatively-Related-Species-from-Seven-Other-Series-in-Solanum-Sect.-Petota-.pdf