Gymnocalycium michoga Gymnocalycium pungens Gymnocalycium schickendantzii var. pectinatum Gymnocalycium schickendantzii subsp. periferalium Gymnocalycium stuckertii Gymnocalycium schickendantzii subsp. bergeri Gymnocalycium pungens Echinocactus stuckertii
World Flora Online, accessed June 20, 2024