Ravindra, B; Kumaravel, P; Selvendran, R; Samuel, Joyce; Kumar, P; Nancy Jassoria; Navneeth, R. S
(Springer, 2020-01)
The importance of the periodicity in sunspot appearance was well recognized by the mid-19th century. Several observatories around the globe have made the record of sunspots in the form of drawings and preserved them safely ...