Applied Mathematics Letters
Applied Mathematics Letters > 2009 > 22 > 11 > 1694-1699
Applied Mathematics Letters > 2009 > 22 > 12 > 1798-1802
Applied Mathematics Letters > 2013 > 26 > 6 > 659-663
Applied Mathematics Letters > 2009 > 22 > 11 > 1694-1699
Applied Mathematics Letters > 2009 > 22 > 12 > 1798-1802
Applied Mathematics Letters > 2013 > 26 > 6 > 659-663