Question:
Which employer did Margaret Atwood work for in Apr, 1971?

Context:
 Margaret Atwood works for Sir George Williams University from Jan, 1967 to Jan, 1968. 
 Margaret Atwood works for University of British Columbia from Jan, 1964 to Jan, 1965. 
 Margaret Atwood works for University of Alberta from Jan, 1969 to Jan, 1970. 
 Margaret Atwood works for York University from Jan, 1971 to Jan, 1972.

Answer:
York University