The State Duma (), commonly abbreviated in Russian as Gosduma (), is the lower house of the Federal Assembly of Russia, while the upper house is the Federation Council. The Duma headquarters are located in central Moscow, a few steps from Manege Square. Its members are referred to as deputies. The State Duma replaced the Supreme Soviet as a result of the new constitution introduced by Boris Yeltsin in the aftermath of the Russian constitutional crisis of 1993, and approved in a nationwide referendum. In the 2007 and 2011 Russian legislative elections a full party-list proportional representation with 7% electoral threshold system was used, but this was subsequently repealed. The legislature's term length was initially 2 years in the 1993–1995 elections period, and 4 years in 1999–2007 elections period; since the 2011 elections the term length is 5 years. History Early history The history of the duma dates back to the boyar dumas of Kievan Rus' and Muscovite Russia as well Tsarist Russia. The State Duma of the Russian Empire was founded in 1905 after the violence and upheaval in the Russian Revolution of 1905 and was Russia's first elected parliament. The first two attempts by Tsar Nicholas II (1868-1918) to make it active were ineffective. Subsequently, each of these Dumas was dissolved after only a few months. The third Duma was the only one to last until the end of its five-year term. After the 1907 electoral reform, the third Duma, elected in November 1907, was largely made up of members of the upper classes, as radical influences in the Duma had almost entirely been removed. The establishment of the Duma after the 1905 Revolution was to herald significant changes to the previous Russian Imperial autocratic system. Furthermore, the Duma was later to have an important effect on Russian history, as it was one of the contributing factors in the February Revolution of 1917, the first of two that year, which led to the abolition of the Tsarist autocracy in Russia and the overthrow of the Tsardom. Recent history 1990s Following the dissolution of the Soviet Union and the 1993 Russian constitutional crisis, the Soviet system of government was abolished and a new Constitution was introduced and approved by a referendum. The new Charter transformed the Russian Federation into a federal semi-presidential republic, with a bicameral parliament composed by the State Duma and the Federation Council. In the December