“…This result was announced as a conjecture in [15], [16] and [17], and also was mentioned in [4]. As approaches to the aimed result, we presented in [14] and [15] several particular positive cases, namely, when either one of the factors is a π-group ([14, Theorem 1, Lemma 1]), or they are soluble groups ([15, Theorem 2]), or when the factors have coprime orders ([15, Proposition 1]).…”