@article{10_4064_cm_45_2_277_285,
     author = {C. C. Travis and G. F. Webb},
     title = {Perturbation of strongly continuous cosine family generators},
     journal = {Colloquium Mathematicum},
     pages = {277--285},
     publisher = {mathdoc},
     volume = {45},
     number = {2},
     year = {1981},
     doi = {10.4064/cm-45-2-277-285},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-45-2-277-285/}
}