Baradey, Y., M. N. A. Hawlader, A. F. Ismail, and M. Hrairi. “WASTE HEAT RECOVERY IN HEAT PUMP SYSTEMS: SOLUTION TO REDUCE GLOBAL WARMING”. IIUM Engineering Journal, Vol. 16, no. 2, Nov. 2015, pp. 31-42, doi:10.31436/iiumej.v16i2.602.