COMBINING the firsthand observations of a Reuters correspondent with scholarly research, Boris Yeltsin: From Bolshevik to Democrat, by John Morrison (Dutton, 303 pp., $20), is a compelling account of the Russian leader's career. It tells of his poverty-stricken childhood and bare-knuckles rise to prominence, interweaving the ebb and flow of contemporary Soviet politics, especially the stormy relationship between Yeltsin and Mikhail Gorbachev.In Twilight of Empire: Inside the Crumbling Soviet Bloc, by Robert Cullen (Atlantic Monthly Press, 310 pp., $21.95), the former Moscow correspondent for Newsweek offers a series of essays chronicling his travels and interviews around the Soviet Union. The essays are remarkable for their depth and the frank remarks made by many Soviet citizens. I Hope: Reminiscences and Reflections, by Raisa Gorbachev, Mikhail Gorbachev's wife (HarperCollins, 224 pp., $20) could have given much insight into the character of the Soviet leader. Sadly, it does not. There is some interesting material about their early life as students and struggling just-marrieds. All the students at Moscow University devised techniques for traveling free on the capital's trains and Metro, but Mrs. Gorbachev is coy about whether her husband did the same. And as an ill-paid bureaucrat in Stavropol, Mr. Gorbachev kept a keen eye open during his travels for consumer goods that were in short supply. But aside from such human details, his book is stilted and clumsy, marred by long interj ections and digressions from the interviewer to whom Mrs. Gorbachev chose to dictate her memoirs. For a New Russia: The Mayor of St. Petersburg's Own Story of the Struggle for Justice and Democracy, by Anatoly Sobchak (Free Press, 191 pp., $22.95), is by one of the most interesting men in the USSR, the mayor of St. Petersburg (formerly Leningrad). It offers his political philosophy and a fascinating account of where he was and what he did during the abortive August coup attempt. Rebuilding Russia: Reflections and Tentative Proposals, by Aleksandr Solzhenitsyn (Farrar Straus & Giroux, 96 pp., $14.95), is an essay-booklet by the long-exiled Soviet writer, who applies his controversial views to Russia's future. He is for shedding the republics, disbanding the KGB, and allowing private ownership of property but has reservations about direct elections and questions about the value of the market economy. Russia Shakes the World, by Gary Hart (HarperCollins, 255 pp., $22), is the former senator's analysis of the current Soviet revolution and his view of how the United States should apply its newly liberated energies to problems at home.