@article{10_4153_CMB_1979_003_x,
     author = {Cheng, Sui-Sun},
     title = {Nonoscillatory {Solutions} of x(m) = {(-1)mQ(t)x}},
     journal = {Canadian mathematical bulletin},
     pages = {17--21},
     year = {1979},
     volume = {22},
     number = {1},
     doi = {10.4153/CMB-1979-003-x},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1979-003-x/}
}