matter, we feel that the present book can be considered as an excellent reference for those students starting their research work in the field of solar system radio astronomy. All lecturers tried to present their subjects in a simple form based upon their exten­ sive personal experience, but without emphasizing their personal research. We must recognize that it was an excellent achievement for them to keep their text exactly at the level indicated by the Program Director, and outlined by the gen­ eral program of Advanced Study Institutes of NATO. We are deeply grateful to all the invited scientists for their outstanding contributions in lecturing on their subjects in a clear and authoritative manner. The Scientific Affairs Division of NATO, in its aid to basic research, spon­ sors various programs. Among them is the Program of Advanced Study Institutes.