1. Day-Night Variations in Malate Concentration, Osmotic Pressure, and Hydrostatic Pressure in Cereus validus. Lüttge U and Nobel PS (1984). Plant Physiol. PubMed: 16663708
2. Influence of Applied NaCl on Crassulacean Acid Metabolism and Ionic Levels in a Cactus, Cereus validus. Nobel PS et al (1984). Plant Physiol. PubMed: 16663707