@article{JMAG_2011_7_4_a1,
     author = {K. S. Khalina},
     title = {On the {Neumann} boundary controllability for the non-homogeneous string on a segment},
     journal = {\v{Z}urnal matemati\v{c}eskoj fiziki, analiza, geometrii},
     pages = {333--351},
     year = {2011},
     volume = {7},
     number = {4},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JMAG_2011_7_4_a1/}
}