O'Connor, John J.; Robertson, Edmund F. (August 2004). "Berlin Academy of Science". MacTutor History of Mathematics. Archived from the original on 12 January 2008. Retrieved 4 January 2008.
O'Connor, John J.; Robertson, Edmund F. (November 1999). "William Braikenridge". MacTutor History of Mathematics. Archived from the original on 2019-08-27. Retrieved 2008-01-04.
O'Connor, John J.; Robertson, Edmund F. (August 2004). "Berlin Academy of Science". MacTutor History of Mathematics. Archived from the original on 12 January 2008. Retrieved 4 January 2008.
O'Connor, John J.; Robertson, Edmund F. (November 1999). "William Braikenridge". MacTutor History of Mathematics. Archived from the original on 2019-08-27. Retrieved 2008-01-04.