{{el}}* Maor, Eli, ''[http://www.pupress.princeton.edu/books/maor/ Trigonometrio]'', ISBN 0-691-09541-8.
{{el}}* Needham, Tristan, [http://www.usfca.edu/vca/PDF/vca-preface.pdf "Enkonduko"]" al ''[http://www.usfca.edu/vca/ Vida Kompleksa Analitiko]''. (1999). ISBN 0-19-853446-9.
{{el}}* O'Connor, J.J., kaj E.F. Robertson, [http://www-gap.dcs.st-and.ac.uk/~history/HistTopics/Trigonometric_functions.html Trigonometriaj funkcio].
{{el}}* O'Connor, J.J., kaj E.F. Robertson, [http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Madhava.html "Madhava de Sangamagramma"].
{{el}}* Pearce, Ian G., [http://www-history.mcs.st-andrews.ac.uk/history/Projects/Pearce/Chapters/Ch9_3.html "Madhava de Sangamagramma"].
{{el}}* [http://mathworld.wolfram.com/Tangent.html Tangento] je ''MathWorld''.
