This book is mainly expository work but chapter three carries (3.1.28), (3.1.29) and (3.1.38) a little original calculation. The various chapters are organized as follows,Chapter one contains a brief review of general relativity.Chapter two Contains space and time manifold.Chapter three Contains an Exact Solution of Einstein"s Equations where the theories of modern physics generally involve a mathematical model,defined by a certain set of rules for translating the mathematical result into meaningful statements about the physical world.Chapter four Contains a cosmological constant introduced into the description of the universe in terms of the general theory of relativity by Albert Einstein in order to make those models static.Chapter five deals with Friedman Model with cosmological constant and Chapter six contains the Cosmological Constant where cosmological constant was invented by Albert Einstein in 1917 already mention in different chapters. Einstein used his equations of general relativity to make cosmological models. He found that the model could not stay the some size, but needed to be either expansion or contraction. Это и многое другое вы найдете в книге Studies On Einstein’s Field Equations And Cosmological Constant (Sayed Allamah Iqbal)