Longly, B., & Louant, BP. (1981). Microgametogenesis and Megagametogenesis in Cichorium-intybus L - Successive Stages and Some Symptoms of Apospory. Acta Societatis Botanicorum Poloniae, 50(1-2), 205-211. https://hdl.handle.net/2078.5/144763 (Original work published 1981)