Ricceri, Carlo, Benito Moraldo, and Giuseppe Pisani. 2018. “Contribution to the Knowledge of Viola L. Sect. Melanium Ging. (Violaceae) of the Central-Southern Apennine and Sicily (Italy)”. Bullettin of the Gioenia Academy of Natural Sciences of Catania 51 (381), FP181-FP234. https://bollettino.gioenia.it/index.php/gioenia/article/view/5.