Find the names of nurses who are on call.
SELECT DISTINCT T1.name FROM nurse AS T1 JOIN on_call AS T2 ON T1.EmployeeID  =  T2.nurse
SELECT DISTINCT T1.name FROM nurse AS T1 JOIN on_call AS T2 ON T1.EmployeeID  =  T2.nurse
[{'Name': 'Carla Espinosa'}, {'Name': 'Laverne Roberts'}, {'Name': 'Paul Flowers'}]