Eder A., Stichler W., Ziegler H., Mechanismen der CO₂-Fixierung bei Euphorbia trigona Haw. und einigen Pachypodium-Arten, Biochemie und Physiologie der Pflanzen, 1981, 176(1):1-12, doi: 10.1016/S0015-3796(81)80003-0
Physiological experiments compare Euphorbia trigona with Pachypodium brevicaule, P. horombense and P. lamerei. Gas exchange, isotopic composition and carbon metabolism contrast C3 in the tested Pachypodium with differing photosynthetic rhythms in Euphorbia leaves and stems.