@article{10_4064_sm_44_5_411_416,
     author = {S. Rolewicz},
     title = {On optimal observability of linear systems with infinite-dimensional states},
     journal = {Studia Mathematica},
     pages = {411--416},
     year = {1972},
     volume = {44},
     number = {5},
     doi = {10.4064/sm-44-5-411-416},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm-44-5-411-416/}
}