Question: Rose Mary Woods and Harry Robbins "Bob" Haldeman both had ties to President Richard Nixon, how long did Rose Mary Woods work for him?

Context paragraphs:
Zilch memo: A memorandum known as the Zilch memo was an American government document sent by National Security Advisor Henry Kissinger to President Richard Nixon on January 3, 1972, about the military situation in Laos during the Vietnam War.  On the memo, in his own handwriting, Nixon described the decade-long bombing campaign by the United States in Southeast Asia as a "failure," having achieved "zilch," despite public comments to the contrary.  Just the day before, January 2, Nixon told CBS News reporter Dan Rather in an interview that the bombing was "very, very effective."  Previously missing from the Richard Nixon Library, the memo was discovered in the possession of Alexander Butterfield, who served as the Deputy Assistant to President Nixon from 1969 to 1973, by "Washington Post" reporter Bob Woodward, who subsequently published it in his 2015 book "The Last of the President's Men".

H. R. Haldeman: Harry Robbins "Bob" Haldeman (October 27, 1926 – November 12, 1993) was an American political aide and businessman, best known for his service as White House Chief of Staff to President Richard Nixon and his consequent involvement in the Watergate Affair.

United States v. Nixon: United States v. Nixon, 418 U.S. 683 (1974), was a landmark United States Supreme Court decision which resulted in a unanimous 8–0 ruling against President Richard Nixon, ordering him to deliver presidential tape recordings and other subpoenaed materials to the District Court.  Issued on July 24, 1974, the ruling was important to the late stages of the Watergate scandal, when there was an ongoing impeachment process against Richard Nixon.  "United States v. Nixon" is considered a crucial precedent limiting the power of any U.S. president to claim executive privilege.

Rose Mary Woods: Rose Mary Woods (December 26, 1917 – January 22, 2005) was Richard Nixon's secretary from his days in Congress in 1951, through the end of his political career.  Before H. R. Haldeman and John Ehrlichman became the operators of Nixon's presidential campaign, Woods was Nixon's gatekeeper.

United States Balance of trade: The 1920s marked a decade of economic growth in the United States following a Classical supply side policy.  U.S. President Warren Harding signed the Emergency Tariff of 1921 and the Fordney–McCumber Tariff of 1922.  Harding's policies reduced taxes and protected U.S. business and agriculture.  Following the Great Depression and World War II, the United Nations Monetary and Financial Conference brought the Bretton Woods currency agreement followed by the economy of the 1950s and 1960s.  In 1971, President Richard Nixon ended U.S. ties to Bretton Woods, leaving the U.S. with a floating fiat currency.

Hilda Mary Woods: Hilda Mary Woods (1892–1971) MBE, was a British statistician who began work in 1916 at the Medical Research Council's Statistical Research Unit with Major Greenwood ("Major" being his forename, not a military rank).  Subsequently, she would deputize for him in his Directorship of the Unit, where in 1931 Woods and her co-author William Russell published an early textbook on medical statistics ("Introduction to Medical Statistics", reprinted in 1936).  Their practical text was based on lectures given at the London School of Hygiene and Tropical Medicine (LSHTM), as referenced in Hill's 1937 Lancet articles and subsequent seminal text, "The Principles of Medical Statistics".

Nixon v. General Services Administration: Nixon v. General Services Administration, 433 U.S 425 (1977), is a landmark court case concerning the principle of presidential privilege and whether the public is allowed to view a President’s “confidential documents”.  The Presidential Recordings and Materials Preservation Act, signed into law by President Gerald Ford in 1974, ordered that the Administrator of General Services obtain President Richard Nixon’s presidential papers and tape recordings.  In addition, the Act further ordered that government archivists seize these materials.  These archivists would preserve the material deemed historic and return to former President Nixon the materials deemed as private.  Furthermore, this Act stated that material that was preserved could be used in judicial hearings and proceedings.  Immediately after this Act was enacted, Richard Nixon filed a lawsuit in a federal district court claiming that the Act violated the principle of separation of powers, the principle of presidential privilege, Nixon’s personal privacy, his First Amendment right of association, and further asserted that it amounted to a constitutionally prohibited Bill of Attainder.

Hatchet man (politics): In the context of the Watergate scandal, the term hatchet man was used to refer to a trusted and particularly orthodox subordinate tasked by his employer with destroying a political opponent by any means necessary.  Charles Colson was known as a hatchet man for President Richard Nixon, as was H.R. Haldeman, who proudly described himself as "Richard Nixon's 'son of a bitch'".  This use of the term has since become commonplace for anyone who is tasked with conducting distasteful, illegal, or unfair "dirty work" to protect the reputation or power of their employer.

Sisters of St. Mary: The Sisters of St. Mary (S.S.M.) was a former Roman Catholic religious congregation for women based in St. Louis, Missouri that founded hospitals throughout the Midwest.  It was merged with another congregation which had broken off from them shortly after their founding to form the Franciscan Sisters of Mary.  As of May 2013, Sister Rose Mary Dowling, FSM, is the President and thus the ecclesiastical religious superior of the Sisters of St. Mary.

Rose Mary Crawshay: Rose Mary Crawshay (1828–1907) was a British philanthropist.  She was born Rose Mary Yeates in Berkshire in England.  She married Robert Thompson Crawshay in 1846 who was last of the Merthyr Tydfil ironmasters, and became the mistress of Cyfarthfa Castle.

Supporting paragraphs: Rose Mary Woods H. R. Haldeman
Answer: was Richard Nixon's secretary from his days in Congress in 1951, through the end of his political career.