What is Efim Bogolyubov?
[[File:Efim Bogoljubov.jpg|thumb|right|250px|Boguljubov]] [[File:E Bogoljubov A Rubinstein 12th november 1925.JPG|thumb|right|250px|Boguljubov, left, versus [[Akiba Rubinstein]], right, [[Moscow]] 1925]] '''Efim Bogolyubov''' <ref>(Bogoljubov, Bogoljubow) {{lang-ru|Ефи&#769;м Дми&#769;триевич Боголю&#769;бов}}</ref> (14 April 1889 – 18 June 1952) was a [[Ukrainians|Ukrainian]]–[[Germany|German]] [[chess]] [[Grandmaster (chess)|grandmaster]] who won numerous events and played two matches with [[Alexander Alekhine]] for the world championship. His weak point, it is said, was over-optimism, but at his best he was one of the world's leading players.<ref>Hooper D. and Whyld K. 1992. ''The Oxford companion to chess''. 2nd ed, Oxford University Press.</ref><sup>p49</sup> == 1919 to 1939 == After the [[World War I]], he won international tournaments at [[Berlin]] 1919, [[Stockholm]] 1919, Stockholm 1920, [[Kiel]] 1921, and [[Pistyan]] (Pieštany) 1922. He tied for 1st–3rd at Karlsbad ([[Karlovy Vary]]) 1923. In 1924 Bogoljubow briefly returned to Russia, which had since become the Soviet Union, and won consecutive [[USSR]] championships in 1924 and 1925.<ref>[http://www.geocities.com/al2055Km/index.html Russian Chess Base<!-- Bot generated title -->]</ref> He also won at Breslau ([[Wroclaw]]) 1925, and in [[Moscow]] 1925, ahead of a field which included [[Emanuel Lasker]] and [[José Raúl Capablanca]]. In 1926, he emigrated to Germany. He won, ahead of [[Akiba Rubinstein]] that year at Berlin. At [[Bad Kissingen]] 1928, he triumphed (+6 –1 =4) over a field which included Capablanca, [[Nimzovich]] and [[Savielly Tartakower]]. Bogoljubov won two matches against [[Max Euwe]] (both 5.5–4.5) in 1928 and 1928/29 in Holland. He played matches for the [[World Chess Championship]] twice against Alekhine, losing 15.5–9.5 in 1929, and 15.5–10.5 in 1934. He represented Germany at first board in the 4th [[Chess Olympiad]] at [[Prague]] 1931, winning the individual silver medal (+9 –1 =7).<ref>[http://www.olimpbase.org OlimpBase ::