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• Ua Buachalla, Domhnall (Donal Buckley)
• Uganda: Archontology
• Uganda: Governors-General: 1962-1963
• Uganda: Heads of State: 1962-1963
• Uganda: Heads of State: 1963-2020
• Uganda: Polity Style: 1962-2020
• Ukraine (Soviet Republic): Polity Style: 1917-1991
• Ukraine: Archontology
• Ukraine: Chairmen of the Central Council: 1917-1918
• Ukraine: Heads of State: 1918-1920
• Ukraine: Heads of State: 1991-2020
• Ukraine: Sources
• Ukrainian Soviet Socialist Republic: Archontology
• Ukrainian Soviet Socialist Republic: Heads of Provisional Government: 1918-1919
• Ukrainian Soviet Socialist Republic: Heads of State: 1917-1918
• Ukrainian Soviet Socialist Republic: Sources
• United Arab Emirates: Abu Dhabi: Archontology
• United Arab Emirates: Abu Dhabi: Heads of State: 1761-2020
• United Arab Emirates: Abu Dhabi: Polity Style: 1761-2020
• United Arab Emirates: Ajman: Archontology
• United Arab Emirates: Ajman: Heads of State: 1700-2020
• United Arab Emirates: Ajman: Heads of State: 1700-2020
• United Arab Emirates: Ajman: Polity Style: 1700-2020
• United Arab Emirates: Archontology
• United Arab Emirates: Dubai: Archontology
• United Arab Emirates: Dubai: Heads of State: 1800-2020
• United Arab Emirates: Dubai: Polity Style: 1800-2020
• United Arab Emirates: Fujairah: Archontology
• United Arab Emirates: Fujairah: Heads of State: 1900-2020
• United Arab Emirates: Fujairah: Polity Style: 1900-2020
• United Arab Emirates: Glossary
• United Arab Emirates: Heads of State: 1971-2020
• United Arab Emirates: Kalba: Archontology
• United Arab Emirates: Kalba: Heads of State: 1871-1952
• United Arab Emirates: Kalba: Polity Style: 1871-1952
• United Arab Emirates: Polity Style: 1971-2020
• United Arab Emirates: Ras al-Khaimah: Archontology
• United Arab Emirates: Ras al-Khaimah: Polity Style: 1700-2020
• United Arab Emirates: Sharjah: Archontology
• United Arab Emirates: Sharjah: Heads of State: 1800-2020
• United Arab Emirates: Sharjah: Polity Style: 1800-2020
• United Arab Emirates: Umm al-Quwain: Archontology
• United Arab Emirates: Umm al-Quwain: Heads of State: 1775-2020
• United Arab Emirates: Umm al-Quwain: Polity Style: 1775-2020
• United Arab Republic: Archontology
• United Arab Republic: Glossary
• United Arab Republic: Heads of State: 1958-1971
• United Arab Republic: Polity Style: 1958-1961
• United Indonesia: Archontology
• United Indonesia: Heads of State: 1960-1961
• United Indonesia: Polity Style: 1960-1961
• United Kingdom: Archontology
• United Kingdom: Heads of State: 1801-2020
• United Kingdom: Polity Style: 1707-2020
• United Kingdom: Prime Ministers: 1730-2020
• United Kingdom: Prime Ministers: 1905-2020
• United Kingdom: Principal Ministers: 1730-1905
• United States of Indonesia: Archontology
• United States of Indonesia: Heads of State: 1949-1950
• United States of Indonesia: Polity Style: 1949-1950
• United States: Archontology
• United States: Heads of State: 1789-2020
• United States: Notes
• United States: Polity Style: 1781-2020
• United States: Presidents of Congress: 1774-1789
• United States: Sources
• Untitled Document
• Uruguay: Archontology
• Uruguay: Governors: 1814-1817
• Uruguay: Heads of State: 1825-1830
• Uruguay: Heads of State: 1830-1919
• Uruguay: Heads of State: 1952-2020
• Uruguay: Polity Style: 1814-2020
• Uruguay: Presidents of the National Council of Administration: 1919-1933
• Uruguay: Presidents of the Republic: 1919-1952
• Uruguay: Sources
• USSR: Communist Party Leadership: 1917-1991
• USSR: Communist Party: 1917-1952 (Politburo)
• USSR: Communist Party: 1919-1952 (Orgburo)
• USSR: Communist Party: 1919-1991 (Secretariat)
• USSR: Communist Party: 1922-1991 (Leadership history)
• USSR: Communist Party: 1952-1966 (Presidium)
• USSR: Communist Party: 1966-1991 (Politburo)
• USSR: Communist Party: Congresses
• USSR: Communist Party: Orgburo
• USSR: Communist Party: Politburo
• USSR: Communist Party: Presidium
• USSR: Communist Party: Secretariat
• USSR: Communist Party: transitional period: 1917-1919
• USSR: Heads of Government: 1923-1991
• USSR: Party Congresses: 1898-1990
• Uzbekistan (Soviet Republic): Archontology
• Uzbekistan (Soviet Republic): Chairman of the Central Executive Committee: 1925-1938
• Uzbekistan (Soviet Republic): Chairmen of the Presidium of the Supreme Council: 1938-1990
• Uzbekistan (Soviet Republic): President of the Republic: 1990-1991
• Uzbekistan (Soviet Republic): Sources
• Uzbekistan: Archontology
• Uzbekistan: Heads of State: 1991-2020
• Uzbekistan: Polity Style: 1924-2020
• Uzbekistan: Polity Style: 1991-2020
• Uzbekistan: Sources

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