I. Galaxies in Small Groups -- The Photography of Groups of Galaxies -- Velocity Dispersion in Small Systems of Galaxies -- Optical Studies of Small Groups of Galaxies -- Nearby Small Groups of Galaxies -- Observations of high velocity HI clouds in the Local Group -- Hypergalaxies -- N-Body Simulations and the Value of ? -- The Galactic Neighbourhood -- Three dimensional analysis of groups of galaxies -- Interacting Systems -- Encounters of spherical galaxies: N-body simulations and comparison with theoretical predictions -- On the Magellanic Stream, the Mass of the Galaxy and the Age of the Universe -- II. Clusters of Galaxies -- Photoelectric surface photometry of the Coma Cluster -- Radio Properties of Abell Clusters -- Radio Observations of Clusters of Galaxies: The Tail Sources -- Extended radio emission in clusters of galaxies: recent Westerbork observations -- Clusters with extended radio emission at high frequencies -- Radio haloes around galaxies and in clusters -- X-Ray Observations of Clusters of Galaxies -- Gas in Galaxy Clusters -- Computer Simulations of Galaxy Clustering -- III. Large Scale Systems -- The Local Supercluster -- Large Scale Clustering in the Universe -- Results on the Large Scale Distribution of Extragalactic Objects Obtained by the Method of Statistical Reduction -- Has the Universe the Cell Structure? -- The Physical Properties of Large Scale Systems from Optical Observations -- The structure of the Hercules supercluster -- Observations of the large scale distribution of galaxies -- The field luminosity function and nearby groups of galaxies -- Discussion of Methods on Determining the Mean Matter Density of the Universe -- IV. Observational Evidence for Cosmological Evolution -- Quasars and Cosmological Evolution -- The Surface Density of Quasars -- The Large Scale Distribution of Radio Sources -- Search for Primordial Perturbations of the Universe: Observations with Ratan-600 Radio Telescope -- The Quest for Fine-Scale Anisotropy in the Relict Radiation -- Cosmological Information from X-Ray Observations -- Counts of faint galaxies -- The Evolution of Galaxies: Evidence from Optical Observations -- On the Dynamical Evolution of Clusters of Galaxies -- The Epoch of Galaxy Formation -- QSO absorption lines and intergalactic hydrogen clouds -- Fluctuations of the Microwave Background Radiation -- V. The Formation of Structure in the Universe -- The Theory of the Large Scale Structure of the Universe -- The internal structure of protoclusters and the formation of galaxies -- The Whirl Theory of the Origin of Structure in the Universe -- Origin of protogalactic eddies -- Evidence for the gravitational instability picture in a dense Universe -- Primeval clusters of galaxies and the X-ray background -- Observational limits on neutral hydrogen in primordial protoclusters -- Personal View-The Large Scale Structure of the Universe -- Author Index.