Witnesses may be required by order of the court or by subpoenas from the referee, to appear and testify upon any proceedings under this chapter , in the same manner as upon the trial of an issue. [R60, §3379; C73, §3139; C97, §4076; C24, 27, 31, 35, 39, § 11804; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §630.5 ]