Question: What country of origin does Alexei Tikhonov and Maria Petrova have in common?

Context articles: 2013 WTA Tour Championships – Doubles
Alexei Tikhonov
Maria Petrova (rhythmic gymnast)
2009 Kremlin Cup – Women's Doubles
Execution of the Romanov family
Tikhonov's First Government
Ilovaiski family
Premier of the Soviet Union
Yukiko Kawasaki
Maria Petrova (figure skater)

Maria Kirilenko and Nadia Petrova were the defending champions, but chose not to pair up this year.
 Petrova paired up and qualified with Katarina Srebotnik, but they lost in the semifinals to Hsieh Su-wei and Peng Shuai.
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Alexei Vladimirovich Tikhonov (Russian: Алексе́й Влади́мирович Ти́хонов ; born 1 November 1971 in Samara) is a Russian pair skater.
 With partner Maria Petrova, he is the 2000 World champion and a two-time (1999, 2000) European champion.
Maria Petrova (Bulgarian: Мария Петрова ) (born November 13, 1975 in Plovdiv, Bulgaria) is a Bulgarian rhythmic gymnast.
 She is a three-time (1993, 1994, 1995) World All-around champion and a three-time (1992, 1993, 1994) European All-around champion.
Nadia Petrova and Katarina Srebotnik were the defending champions, but Srebotnik chose to participate at the BGL Luxembourg Open instead.Petrova partnered up with Maria Kirilenko, and they won in the final 6-2, 6-2 against Maria Kondratieva and Klára Zakopalová.
The Russian Imperial Romanov family (Tsar Nicholas II, his wife Tsarina Alexandra and their five children Olga, Tatiana, Maria, Anastasia, and Alexei) and all those who chose to accompany them into imprisonment – notably Eugene Botkin, Anna Demidova, Alexei Trupp and Ivan Kharitonov – were shot, bayoneted and clubbed to death in Yekaterinburg on the night of 16-17 July 1918.
 The Tsar and his family were killed by Bolshevik troops led by Yakov Yurovsky under the orders of the Ural Regional Soviet.
 Their bodies were then stripped, mutilated, burned and disposed of in a field called Porosenkov Log in the Koptyaki forest.
The former government of Alexei Kosygin was dissolved following his resignation in October 1980.
 Nikolai Tikhonov took over the office of the Premier.
 The government was dissolved following the nationwide 1984 legislative election.
Ilovaiski (Russian: Иловайский ) was the name of noble family of Don Cossacks origin.
 Mokej Osipovich Ilovaiski being the oldest of known ancestors came on Don at 1675 from the oldest Russian town Temnikov in modern Republic of Mordovia and founded Makiivka so this property was named after its owner.
 His two sons Alexei and Dmitri was owners of Zuevka and Khartsyzk.
 This family owned a lot of lands in Don Voisko and from second half of the 19th century were owners of six coal mines in Makiivka that gives a 20% of total coal of Yuzovka in 1890.
 Twelve of the Ilovski family joined the Napoleonic wars, and the most famous member of the family was Alexei Ilovaiski (1767 — 1842), a Russian General and Don Cossacks Ataman (1823 - 1827).
The office of Premier of the Soviet Union (Russian: Глава Правительства СССР ) was synonymous with head of government of the Union of Soviet Socialist Republics (USSR).
 Twelve individuals became premier over the time span of the office.
 Two of the twelve premiers died in office of natural causes (Vladimir Lenin and Joseph Stalin), three resigned (Alexei Kosygin, Nikolai Tikhonov and Ivan Silayev), and three held the offices of party leader and premier simultaneously (Lenin, Stalin and Nikita Khrushchev).
 The first premier was Lenin, who was inaugurated in 1922 after the Treaty on the Creation of the USSR.
 Ivan Silayev spent the shortest time in office at 126 days in 1991.
 At over fourteen years, Kosygin spent the longest time in office, and became the only premier to head more than two government cabinets; he died shortly after his resignation in 1980.
Yukiko Kawasaki (川崎 由紀子 , Kawasaki Yukiko , born July 31, 1977) is a Japanese figure skater who competed in both singles and pair skating.
 As a pair skater, she competed with Alexei Tikhonov for Japan.
 They are two-time Japanese national champions and won the bronze medal at the 1993 NHK Trophy.
 As a single skater, she competed internationally on the junior and senior levels.
Maria Igorevna Petrova (Russian: Мария Игоревна Петрова ; born 29 November 1977) is a Russian pair skater.
 With partner Alexei Tikhonov, she is the 2000 World champion and a two-time (1999, 2000) European champion.