Spain in the 19th Century

In Spain during the 19th Century there were some Constitutions. But only one was called "la Pepa". Which one?

• 

  The first one, on March 19 1812, was a liberal text.

• 

  In 1837 there was another one, which was also liberal, that was approved with the support of Queen María Cristina of Bourbon.

• In 1869, the third one established a parliamentary monarchy.

• The last one, in 1876, was more conservative than the previous one and allowed alternating the two main political parties (Conservatives and Liberals).