Applied Mathematics Letters
Applied Mathematics Letters > 2012 > 25 > 3 > 600-604
Applied Mathematics Letters > 2012 > 25 > 10 > 1539-1543
Applied Mathematics Letters > 2012 > 25 > 11 > 1744-1749
Applied Mathematics Letters > 2012 > 25 > 3 > 600-604
Applied Mathematics Letters > 2012 > 25 > 10 > 1539-1543
Applied Mathematics Letters > 2012 > 25 > 11 > 1744-1749