Menso Folkerts, Craig G. Fraser, Jeremy John Gray, John L. Berggren, Wilbur R. Knorr (2017), Mathematics, Encyclopaedia Britannica, Quote: "(...) its Hindu inventors as discoverers of things more ingenious than those of the Greeks. Earlier, in the late 6th century BCE, the anonymous Hindu author of an astronomical handbook, the Surya Siddhanta, had tabulated the sine function (...)"
doi.org
Markanday, Sucharit; Srivastava, P. S. (1980). "Physical Oceanography in India: An Historical Sketch". Oceanography: The Past. Springer New York. hlm. 551–561. doi:10.1007/978-1-4613-8090-0_50. ISBN978-1-4613-8092-4., Quote: "There are five important Hindu astronomical books known as Siddhantas. Surya Siddhanta is the third oldest (about the 6th century BC). According to Al-Biruni it was written by Lata. The book is divided into 14 chapters (Table 1). According to Surya Siddhanta the universe is a sphere."
Pingree, David (1971). "On the Greek Origin of the Indian Planetary Model Employing a Double Epicycle". Journal for the History of Astronomy. SAGE Publications. 2 (2): 80–85. Bibcode:1971JHA.....2...80P. doi:10.1177/002182867100200202.
harvard.edu
adsabs.harvard.edu
Pingree, David (1971). "On the Greek Origin of the Indian Planetary Model Employing a Double Epicycle". Journal for the History of Astronomy. SAGE Publications. 2 (2): 80–85. Bibcode:1971JHA.....2...80P. doi:10.1177/002182867100200202.
