  For analytic functions f(z) in the open unit disk U with f(0)=f'(0)-1=0, R.
Singh and S. Singh (Coll. Math. 47(1982), 309-314) have considered some
sufficient problems for f(z) to be univalent in U. The object of the present
paper is to discuss some sufficient problems for f(z) to be some classes of
analytic functions in U.
