@article{10_4064_cm109_1_12,
     author = {Y. N. Aliyev},
     title = {Minimality of the system of root functions
 of {Sturm{\textendash}Liouville} problems with decreasing
 affine boundary conditions},
     journal = {Colloquium Mathematicum},
     pages = {147--162},
     publisher = {mathdoc},
     volume = {109},
     number = {1},
     year = {2007},
     doi = {10.4064/cm109-1-12},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm109-1-12/}
}