(FORTUNE Magazine) – At first glance one might wonder at the need for yet another book about Armand Hammer. A genius at self-promotion, the 91-year-old CEO of Occidental Petroleum has been responsible for no fewer than four books about himself, including an autobiography (Hammer, subsidized by Occidental and ghosted by a British journalist) that was a surprise best-seller two years ago. But like most such ventures in admiring self-assessment, these volumes betray an alarming tilt toward hagiography and suffer as well from dismaying lacunas in chronicling their subject's extraordinary career. Few lives have called so insistently for unauthorized appraisal, and it has finally arrived in the form of a hefty, 501-page volume by Steve Weinberg entitled Armand Hammer: The Untold Story (Little Brown, $22.95). It is a good book, iconoclastic by necessity but judicious in tone, skeptical rather than hostile, on occasion too detailed but written with verve and an eye for the telling anecdote. The author did not receive the cooperation of Dr. Hammer, who is so upset by the volume, which he says is full of errors, that he has threatened to sue for libel. (The book has already appeared in stores, and the controversy will likely boost sales.) Weinberg seems to have talked to every possible source who would talk to him; he reports that he conducted more than 700 interviews, in person and by mail and telephone. The author, an associate professor at the University of Missouri School of Journalism, has mastered the full apparatus of scholarship. His text is carefully annotated, and he has burrowed through the archival remains of numberless Hammer acquaintances whose private papers repose in research libraries. That search has yielded many gems; even the small ones are revealing. Before Hammer went to the Soviet Union in 1961, for example, he armed himself with a letter of introduction to Nikita Khrushchev from Eleanor Roosevelt. In his autobiography Hammer merely states that Mrs. Roosevelt was kind enough to write a letter. Weinberg provides the full story. Hammer had his brother Victor ask Mrs. Roosevelt for the letter, apparently because Victor was on better terms with her, but Armand thoughtfully sent along a draft. He proposed that Mrs. Roosevelt say, among other things, that ''Dr. Hammer was a friend of my husband and myself and my sons and has visited us in the White House and we have visited him in his home. We hold him in high esteem.'' Mrs. Roosevelt, however, was evidently unwilling to claim Hammer as a friend, for she deleted the reference to ''myself'' and also changed both uses of the pronoun ''we'' to ''they.'' The book's achievement is to clear up the major mystery about the fabulous doctor: How did he do it? How did an unknown immigrant's son from the Bronx win the regard of Soviet leaders from Lenin to Gorbachev, become a sometime adviser to Presidents from Roosevelt to Reagan, not to speak of a friend to Prince Charles, all the while amassing a fortune from such varied pursuits as running concessions in the Soviet Union, peddling art, breeding cattle, manufacturing liquor, and in his later years, building a giant international oil company out of a nondescript little outfit called Occidental Petroleum? The core of the mystery, of course, has not been Hammer's great entrepreneurial success so much as his elaborate web of personal associations. Biographer Weinberg unravels the mystery, displaying the complex amalgam of daring, doggedness, guile, psychological astuteness, sycophancy, opportunism, and sheer chutzpah that is Hammer. Without question he has always been a man of many talents. While earning a medical degree at Columbia University he took over his father's ailing pharmaceutical business in New York City and, according to Hammer, made his first million. But no one would have imagined that he would become one of the country's business titans. The family background was certainly unpromising. His father, Julius, Russian born and also a doctor, had been an active member of the Socialist Labor Party and thereafter an early American Communist. Young Hammer seems never to have shared his father's political faith, except perhaps early on: Weinberg has discovered that at age 18 Armand signed an SLP membership application, but thinks it reflects the father's zealousness more than the son's conviction. Armand, however, shrewdly took every advantage of his father's connections. Among his other activities, Julius worked for the unofficial Soviet mission to the U.S. When Armand went to the Soviet Union in 1921 (he was ostensibly a medical volunteer but always had an eye cocked for a business deal) he was warmly welcomed by his father's political cronies, who constituted what might be called a Bolshie Old Boy network. Lenin soon called for him; they talked for an hour or more about the Soviet need for foreign business assistance, and Hammer later received a photo of the old man inscribed in English to ''Comrade Armand Hammer.'' The photo is reproduced in two of Hammer's official biographies (without any indication that he tried to correct Comrade Lenin's faulty impression of his political sympathies). With such backing, he was soon running an asbestos mine, manufacturing pencils, and representing a host of American companies in the Soviet Union. He had come initially for a few months but stayed for nine years, abandoning his budding medical career. He brought over his parents, and all the Hammers lived in grand style. Hammer finally sold his business to the Soviets and returned to the U.S. in 1930, after Stalin started clamping down on foreign concessionaires. Hammer never met Stalin and had the wit not to try. But he exploited his Lenin connection to the hilt after he returned to the Soviet Union in 1961. IN THE U.S., Hammer initially had no top-flight connections to grease the path to success. He also seems to have had no left-wing links. Hammer concentrated on business, at first the art business; he and his brother Victor had collected heaps of Czarist art objects on the cheap, which they sold throughout the country. He had prospered in a variety of fields when in 1956, at age 57, he stumbled onto Occidental Petroleum and found his true calling. He showed remarkable daring, soon blessed with success, as a wildcatter and later as a negotiator for foreign oil concessions, cementing a Libyan connection (before Qaddafi came to power) that brought Occidental into the big time. While expanding his business Hammer pursued a parallel passion: to vault into the topmost echelon of American political society. He was always exploiting social opportunities, pyramiding introductions, lobbying to get the ear of whoever was in power, and in later years lending his art collection for exhibits and making generous charitable contributions to gain the attention of prospective admirers. By 1985 he had contributed $14 million to Prince Charles's favorite charities and had become a buddy, while also winning a lot of publicity in Britain. Weinberg has a number of entertaining stories about Hammer's energetic campaigns to win admittance to the White House. He pulled all the strings at his disposal to get a session with Roosevelt in 1940. FDR was a bit derisive / about him at a press conference, but Hammer later claimed credit for the lend- lease proposal to aid Britain, which he says he discussed with Roosevelt -- a claim that Weinberg maintains the record does not bear out. Hammer wangled an audience with Truman to discuss famine relief in Europe, and Truman put him on a committee. As a major campaign supporter Hammer had entree to the White House under Carter, whom he also supported in the 1980 election. This involvement initially froze him out of the Reagan White House, but Hammer sought to repair the damage by stepping up his philanthropic presence in the capital (including $20,000 for Nancy Reagan's White House redecoration fund) to the point where he could not be overlooked. At the beginning of his second term, Reagan wrote Hammer, ''I value your insights on our policy toward the Soviet Union'' and instructed national security adviser Robert McFarlane to pick his brain on the subject of world peace. Along the way, of course, Hammer has had his pratfalls. Under his leadership Occidental has been the subject of four investigations by the SEC, resulting in consent decrees in which the company was enjoined from actions in the future that it neither affirmed nor denied having done in the past -- a formulation that always leads cynical observers to infer guilt. One practice that distressed the SEC involved Hammer's insistence that several Oxy Pete directors sign undated letters of resignation, a tactic that helped insure his control. Hammer's autobiography overlooks the SEC investigations; Weinberg doesn't. WITHOUT QUESTION Hammer's most serious problem was his guilty plea in 1976 to three misdemeanor counts involving an illegal political contribution of $54,000 to Richard Nixon's presidential campaign in 1972. Hammer claimed to be innocent and maintained that he pled guilty because of his parlous heart condition; he appeared in court in a wheelchair to enter his plea. An understanding judge gave him a fine and probation, with no jail time. The defendant made a speedy recovery and is still going strong. Weinberg's carefully reasoned inference: He was guilty as charged. For years Hammer vainly lobbied the Reagan White House for a pardon. Last August 14, President Bush granted one. That is the last line in Weinberg's book. He apparently had no opportunity, so close to publication, to add details revealed in the Los Angeles Times and Manhattan Lawyer. Both publications pointed out that most pardons are not declarations of innocence but come after the expression of remorse by the culprit and the Justice Department's determination that he or she has led an exemplary life. Yet Hammer refused to express remorse for a crime for which he said he was blameless. He wanted a rarely granted type of pardon based on a presidential finding of innocence. Both the Reagan and Bush Administrations refused. Hammer's lawyers withdrew his unusual request a few months ago, asking instead for an ordinary pardon. After he got it, Hammer nonetheless claimed vindication. The claim was not true -- but like so much in Hammer's record, it makes good copy.

BOX: EXCERPT: A weapon ((for maintaining control of Occidental Petroleum's board)) was the sheaf of undated resignation letters from directors that Hammer possessed. The directors knew the practice was wrong -- Hammer had received specific legal advice against it -- but they failed to speak out publicly against him. Of all ((Hammer's)) Occidental vanity ventures, the film company probably was the most egregiously self-promoting. One of the company's earliest efforts . . . contained footage of Hammer with the leaders of Egypt, England, Hungary, Poland, Peru, Pakistan, Abu Dhabi, and the United States.