“…of order 3 is a more difficult problem, and non-sharp bounds for |H 3 (1) (f )| have been found by various authors, e.g., [1,3,18,25]. We note that using a result in [11], some authors [2,8,9,10,12,17,19] have obtained sharp bounds for |H 3 (1) (f )| for certain subclasses of univalent functions.…”