From September 5 until September 9, 1968, the IVth Colloquium on Variable Stars was held in Budapest, Hungary. The Colloquium was organized by a committee consisting of G.H. Herbig (President), A. Boyarchuk, M.W. Feast, D. McNamara, J.E. Merrill, D.J.K. O'Connell, V. Tsessevich, W. Wenzel. The local organization was placed in the hands of a Committee consist ing of members of the Konkoly Observatory, Budapest: L. Detre (Chairman), 1. Almar, Julia Balazs-Detre, K. Barlai, M. Ill, S. Kany6, M. Lovas and of J. Kovacs (Hungarian Academy of Sciences). The Colloquium was attended by about 90 scientists representing Argentina, Austria, Bulgaria, Canada, France, GDR, GFR, Hungary, Italy, The Netherlands, Poland, Roumania, South Africa, Sweden, United Kingdom, U.S.A., U.S.S.R. As chairmen acted at the sessions: M.W. Feast, G.H. Herbig, J. Sahade, A. Boyarchuk, W. Wenzel, F.B. Wood and L. Rosino. The contents of the present volume parallel closely the programme of the individual sessions of the Colloquium.

Astronomy and Astrophysics Abstracts, which appears in semi-annual volumes, is devoted to the re cording, summarizing and indexing of astronomical publications throughout the world. It aims to pre sent a comprehensive documentation of literature in all fields of astronomy and astrophysics. Every effort will be made to ensure that the average time interval between the date of receipt of the original literature and publication of the abstracts will not exceed eight months. This time interval is near to that achieved by monthly issued abstracting journals, compared to which our system of accumulating abstracts for about six months offers the advantage of greater convenience for the user. Volume 2 contains literature published in 1969 and received before March 15, 1970; some older lite rature which was received late and which is not recorded in Volume 1 is also included. The authors of papers who have sent us abstracts on request have effectively contributed to the suc cess of our service. We should like to express our gratitude to them. We acknowledge with thanks con tributions to this volume by Dr. J. Bou~a, who surveyed journals and publications in Czech language and supplied us with abstracts in English, by Dr. B. Onderlicka, Brno, for providing English ab stracts of Russian papers, and by the Commonwealth Scientific and Industrial Research Organization (C.S.I.R.O.), Sydney, for providing titles and abstracts of papers on radio astronomy.

Proceedings of IAU Symposium No. 67 held in Moscow, U.S.S.R., July 29-August 4, 1974

Invited Papers presented at the IAU Colloquium No. 29, held in Budapest, September 1-5, 1975

The Nebular Variables focuses on the nebular variables and their characteristics. Discussions are organized by type of nebular variable, namely, RW Aurigae stars, T Orionis stars, T Tauri stars, and peculiar nebular objects. Topics range from light variations of the stars to their spectroscopic and physical characteristics, spatial distribution, interaction with nebulosity, and evolutionary features. This volume is divided into four sections and consists of 25 chapters, the first of which provides general information on nebular variables, including their stellar associations and their classification into three distinct groups: RW Aurigae, T Orionis and T Tauri variables. These three groups of nebular variables are examined in more detail in the chapters that follow in terms of their light variations, spatial distribution, interaction with nebulosity, and spectroscopic, physical, and evolutionary characteristics. Visual and photoelectric light curves, mass loss determined spectroscopically, luminosities, and stellar radii are considered. The book also explores the possibility that some of the nebulae associated with certain nebular variables have evolved from a protoplanetary disc of material consisting of both gas and solid matter. Peculiar nebular variables such as the long period variable R Aquarii, Herbig-Haro objects, symbiotic variables, and infrared stars are analyzed as well. This book is written primarily for students and teachers of astronomy.

This timely volume provides the first comprehensive survey of cataclysmic variable stars, integrating theory and observation into a single, synthesised text.