@article{RCM_1987__21_1_181801,
     author = {Alan R. Hausrath and Raul F. Manasevich},
     title = {Periodic {Solutions} {Of} {Perioically} {Harvested} {Lotka-Volterra} {Systems.}},
     journal = {Revista colombiana de matematicas},
     pages = {337--345},
     year = {1987},
     volume = {21},
     number = {1},
     zbl = {0662.92017},
     url = {http://geodesic.mathdoc.fr/item/RCM_1987__21_1_181801/}
}