@article{COCV_2012__18_2_501_0,
     author = {Kratz, Werner and Hilscher, Roman \v{S}imon},
     title = {Rayleigh principle for linear hamiltonian systems without controllability},
     journal = {ESAIM: Control, Optimisation and Calculus of Variations},
     pages = {501--519},
     publisher = {EDP-Sciences},
     volume = {18},
     number = {2},
     year = {2012},
     doi = {10.1051/cocv/2011104},
     mrnumber = {2954636},
     zbl = {1254.34120},
     language = {en},
     url = {http://www.numdam.org/articles/10.1051/cocv/2011104/}
}