Title Page

Contents

Characteristic Features of the Cyclic Change of Solar Activity after 1610
A. D. Bonov

On the Dependence of the Height of Prominences on the Solar Cycle and Heliographic Latitude
V. Dermendjiev (in Russian, Summary in English)

On the Space Distribution of Solar Prominences
V. Dermendjiev (in Russian, Summary in English)

Statistical Investigation of Light and Colour Changes of Ap-Stars
R. Radkov (in Russian, Summary in English)

On the Particular Chemical Composition of Ap-Stars
R. Radkov, S. Milcheva

Proper Motions of Bright Red Giants in Globular Clusters. I. The Globular Cluster M 13
N. Spassova (in Russian, Summary in English)

Proper Motions of Bright Red Giants in Globular Clusters. I. The Globular Clusters M 92 and M 3
N. Spassova (in Russian, Summary in English)

On the Nature of the Calibration Curve in Stellar Photographic Photometry
S. Vladimirov (in Russian, Summary in English)

Generalized χ²-Method for Investigation of the Problem for the Existence of Second-Order Clusters of Galaxies. I. Theory
M. Kalinkov (in Russian, Summary in English)

Generalized χ²-Method for Investigation of the Problem for the Existence of Second-Order Clusters of Galaxies. II. Clusters from Abell’s and Zwicky’s Catalogues
M. Kalinkov, B. Tomov (in Russian, Summary in English)