Who was in charge of Mexico at the time of the second revolution?

Twelve presidents ruled Mexico during the 1910 - 1921 revolutionary period. It was a very unstable period of time:

• Porfirio Diaz (1884 - 1911)
• Francisco Leon de la Barra (May - Nov 1911)
• Francisco Madero (1911 - 1913)
• Pedro Lascurain (19 Feb 1913 - from 15 to 55 minutes before resigning to Huerta)
• Victoriano Huerta (1913 - 1914)
• Francisco Carvajal (Jul - Aug 1914)
• Venustiano Carranza (1914 - 1920)
• Eulalio Gutierrez (1914 - 1915) - provisional president
• Roque Gonzalez (Jan - Jun 1915) - provisional president
• Francisco Lagos (Jun - Oct 1915) - provisional president
• Adolfo de la Huerta (May - Nov 1920) - interim president after Carranza was killed
• Alvaro Obregon (1920 - 1924)