@article{NUMA_1990__58_5_133522,
     author = {P.G. Spain and N.J. Young and J.W. Helton},
     title = {Tracking poles and representing {Hankel} operators directly from data.},
     journal = {Numerische Mathematik},
     pages = {641--660},
     publisher = {mathdoc},
     volume = {58},
     number = {5},
     year = {1990},
     zbl = {0726.30003},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1990__58_5_133522/}
}