Ballester, J. L.; Oliver, R.; Baudin, F., "Discovery of the near 158 day periodicity in group sunspot numbers during the eighteenth century", "The Astrophysical Journal", Volume 522, Pages L153-L156, 1999. Paper.
Terradas, J.; Oliver, R.; Ballester, J. L., "Magnetohydrodynamic waves in coronal magnetostatic arcades", "The Astrophysical Journal", Volume 517, Pages 488-496, 1999. Paper.
Oliver,R.; Cadez,V. M.; Carbonell, M.; Ballester,J. L., "Coronal potencial magnetic fields from photospheric sources with finite width", "Astronomy and Astrophysics", Volume 351, Pages 733-740, 1999. Paper.
Ballester, J. L.; Oliver, R.; Baudin, F., "Discovery of the near 158 day periodicity in group sunspot numbers during the eighteenth century", "The Astrophysical Journal", Volume 552, Pages L153-L156, 1999. Paper.