I have attempted to provide reliable calculation bases for absorption refrigeration units of small and very small capacities, as considered for refrigerators. For the periodically operating "wet" and "dry" absorption refrigeration machines, I was able to build upon the works of Linge, Mannes Mann, and Vahl. For the continuous absorption refrigeration units of the Platen Muntens system, which operate with a thermosyphon pump and auxiliary gas, I aimed to establish a closed theory for the thermal calculation of these units, utilizing the works of Bäckström, Buche, Cattaneo, Mawri, Nesselmann, and others. Overall, my goal was to provide the reader of this volume with practical numerical values, which are summarized in numerous tables. It seemed particularly important to me to also consider the practical implementation of the devices and facilities.