Principles of Statistical Radiophysics is a four-volume series that introduces the newcomer to the theory of random functions. It aims at providing the background necessary to understand papers and monographs on the subject and to carry out independent research in the fields where fluctuations are of importance, e.g. radiophysics, optics, astronomy, and acoustics. Volume 3, Elements of Random Fields, gives the basic mathematical definitions, general properties and specific forms of random fields, the generalization from correlation theory to random fields. It deals with stochastic partial differential equations, wave scattering at a chaotic screen, single scattering in random media and thermal fluctuations and radiation of electromagnetic fields.