@article{RCM_2015_49_1_a9,
     author = {Nicolas Andruskiewitsch and Monique Muller},
     title = {Examples of {Extensions} of {Hopf} {Algebras}},
     journal = {Revista colombiana de matematicas},
     pages = {193--211},
     publisher = {mathdoc},
     volume = {49},
     number = {1},
     year = {2015},
     url = {http://geodesic.mathdoc.fr/item/RCM_2015_49_1_a9/}
}