Excerpts of Right to Survive: Human Rights in Nicaragua (Catholic Institute for International Relations, London: 1987, pp. 25-31.) will provide you with a summary of the Somoza's dictatorship up to 1979.
2)

To provide you with information on the political developments after the Sandinista revolution, please find attached excerpts of Nicaragua: Revolution in the Family (Shirley Christian, Vintage Books, New York: 1986, pp.139-158.) This chapter discusses all the political developments after the revolution and discusses the Sandinista political platform. Likewise, the Amnesty International Report 1980 (Amnesty International Publications, London: 1980) will provide you with information regarding the treatment of political prisoners and dissidents by the Sandinista government soon after the revolution.