@article{RCM_2008_42_1_a5,
     author = {Ju\'an Rada Universida de los Andes and Merida and Venezuela},
     title = {Nonderogatory directed windmills},
     journal = {Revista colombiana de matematicas},
     pages = {61--66},
     publisher = {mathdoc},
     volume = {42},
     number = {1},
     year = {2008},
     url = {http://geodesic.mathdoc.fr/item/RCM_2008_42_1_a5/}
}