Institution: | 1.Department of Mathematics,IES Ramón Caama?o,Muxía,Spain;2.Department of Mathematics,IES María Sarmiento,Viveiro,Spain;3.Faculty of Mathematics,University of Santiago de Compostela,Santiago de Compostela,Spain;4.Department of Mathematics,IES de Ribadeo Dionisio Gamallo,Ribadeo,Spain |