You will be given a definition of a task first, then some input of the task.
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.

He was also involved in work on semiconductor diode s, which were the forerunners of the revolution in electronics brought about by the advent of solid-state semiconductor components. In 1945 he joined the National Acoustic Laboratories where he worked on the design and construction of hearing aids for children. Aitchison was appointed as Senior Lecturer in Communications Engineering at the University of Sydney, which was the start of _his_ 25-year teaching experience at that institution, culminating in his appointment as Associate Professor. <sep>, Pronoun: his
Output:
Aitchison