@article{MZ_1975__143_172234,
     author = {Shiu-Yuen Cheng},
     title = {Eigenvalue {Comparison} {Theorems} and {Its} {Geometric} {Applications.}},
     journal = {Mathematische Zeitschrift},
     pages = {289--297},
     year = {1975},
     volume = {143},
     zbl = {0329.53035},
     url = {http://geodesic.mathdoc.fr/item/MZ_1975__143_172234/}
}