Published in Revista De La Academia Canaria De Ciencias, in 1990, in volume 2, issue 1, pages 15-22

Published in Revista De La Academia Canaria De Ciencias, in 1990, in volume 2, issue 1, pages 71-79

Published in Revista De La Academia Canaria De Ciencias, in 1990, in volume 2, issue 1, pages 81-92

Published in Revista De La Academia Canaria De Ciencias, in 1990, in volume 2, issue 1, pages 99-120

Published in Revista De La Academia Canaria De Ciencias, in 1990, in volume 2, issue 1, pages 171-190