@article{NUMA_1978__30_132559,
     author = {G.J. Cooper and F.C.P. Whitworth},
     title = {Liapunov {Functions} and {Error} {Bounds} for {Approximate} {Solutions} of {Ordinary} {Differential} {Equations.}},
     journal = {Numerische Mathematik},
     pages = {411--414},
     publisher = {mathdoc},
     volume = {30},
     year = {1978},
     zbl = {0367.34040},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1978__30_132559/}
}