“…New ideas were proposed by Rao [70][71][72][73][74][75][76] and Chen [77][78][79][80][81][82]. Other notable workers were Le Van et al [83], Tzafestas [84], Chen [85][86][87][88], Mahapatra [89], Paraskevopoulos [90], Moulden [91], Deb and Datta [92][93][94], Lewis [95], Marszalek [96], Dai and Sinha [97], Deb et a/ [98-1 00] and others.…”