Given the task definition and input, reply with output. In this task, you will be presented with a text and a pronoun. You should write the name that the pronoun refers to. Position of the pronoun in the text is showed within two "_"s.

Carrillo developed an easy method for notation, which would help people not familiar with previous forms of notation to quickly learn to read and write music. To show how easy the new writing system was, Carrillo gave two New York elementary school boys, who had no prior knowledge of Sonido 13, a simple work by Bach to convert to _his_ notation system. <sep>, Pronoun: his
Carrillo