Hall, Arthur Graham; Frink, Fred Goodrich (јануар 1909). „Chapter VII. The General Angle [55] Signs and Limitations in Value. Exercise XV.”. Написано на Ann Arbor, Michigan, USA. Trigonometry. Part I: Plane Trigonometry. New York, USA: Henry Holt and Company / Norwood Press / J. S. Cushing Co. - Berwick & Smith Co., Norwood, Massachusetts, USA. стр. 73. Приступљено 2017-08-12.CS1 одржавање: Формат датума (веза)
Roger Cotes died in 1716. By 1722, his cousin Robert Smith had collected and published Cotes' mathematical writings in a book, Harmonia mensurarum … . In a chapter of editorial comments by Smith, he gives, for the first time, the value of one radian in degrees. See: Roger Cotes with Robert Smith, ed., Harmonia mensurarum … (Cambridge, England: 1722), chapter: Editoris notæ ad Harmoniam mensurarum, top of page 95. From page 95: After stating that 180° corresponds to a length of π (3.14159…) along a unit circle (i.e., π radians), Smith writes: "Unde Modulus Canonis Trigonometrici prodibit 57.2957795130 &c. " (Whence the unit of trigonometric measure, 57.2957795130… [degrees per radian], will appear.)
For a debate on this meaning and use see:Brownstein, K. R. (1997). „Angles—Let's treat them squarely”. American Journal of Physics. 65 (7): 605—614. Bibcode:1997AmJPh..65..605B. doi:10.1119/1.18616., Romain, J.E. (1962). „Angles as a fourth fundamental quantity”. Journal of Research of the National Bureau of Standards Section B. 66B (3): 97. doi:10.6028/jres.066B.012., LéVy-Leblond, Jean-Marc (1998). „Dimensional angles and universal constants”. American Journal of Physics. 66 (9): 814—815. Bibcode:1998AmJPh..66..814L. doi:10.1119/1.18964., and Romer, Robert H. (1999). „Units—SI-Only, or Multicultural Diversity?”. American Journal of Physics. 67 (1): 13—16. Bibcode:1999AmJPh..67...13R. doi:10.1119/1.19185.
google.co.uk
books.google.co.uk
Isaac Todhunter, Plane Trigonometry: For the Use of Colleges and Schools, p. 10, Cambridge and London: MacMillan, 1864 OCLC500022958
For a debate on this meaning and use see:Brownstein, K. R. (1997). „Angles—Let's treat them squarely”. American Journal of Physics. 65 (7): 605—614. Bibcode:1997AmJPh..65..605B. doi:10.1119/1.18616., Romain, J.E. (1962). „Angles as a fourth fundamental quantity”. Journal of Research of the National Bureau of Standards Section B. 66B (3): 97. doi:10.6028/jres.066B.012., LéVy-Leblond, Jean-Marc (1998). „Dimensional angles and universal constants”. American Journal of Physics. 66 (9): 814—815. Bibcode:1998AmJPh..66..814L. doi:10.1119/1.18964., and Romer, Robert H. (1999). „Units—SI-Only, or Multicultural Diversity?”. American Journal of Physics. 67 (1): 13—16. Bibcode:1999AmJPh..67...13R. doi:10.1119/1.19185.
Protter, Murray H.; Morrey, Charles B., Jr. (1970), College Calculus with Analytic Geometry (2nd изд.), Reading: Addison-Wesley, стр. APP-4, LCCN76087042
nih.gov
ncbi.nlm.nih.gov
„SI units need reform to avoid confusion”. Editorial. Nature. 548 (7666): 135. 7. 8. 2011. PMID28796224. doi:10.1038/548135b.CS1 одржавање: Формат датума (веза)
O'Connor, J. J.; Robertson, E. F. (фебруар 2005). „Biography of Roger Cotes”. The MacTutor History of Mathematics. Архивирано из оригинала 2012-09-24. г. Приступљено 2006-04-21.CS1 одржавање: Формат датума (веза)
O'Connor, J. J.; Robertson, E. F. (фебруар 2005). „Biography of Roger Cotes”. The MacTutor History of Mathematics. Архивирано из оригинала 2012-09-24. г. Приступљено 2006-04-21.CS1 одржавање: Формат датума (веза)
wolfram.com
mathworld.wolfram.com
Weisstein, Eric W. „Radian”. mathworld.wolfram.com (на језику: енглески). Приступљено 2020-08-31.
worldcat.org
Isaac Todhunter, Plane Trigonometry: For the Use of Colleges and Schools, p. 10, Cambridge and London: MacMillan, 1864 OCLC500022958
Frederick Sparks, Longmans' School Trigonometry, p. 6, London: Longmans, Green, and Co., 1890 OCLC877238863 (1891 edition)