I am writing a report and as part of it I need to prove the property that for a point $P$ on a hyperbola, the tangent to the hyperbola at $P$ bisects the angle $\angle F_1PF_2$ where $F_1$ and $F_2$ are the foci of the hyperbola.

Wikipedia has the following proof which is pretty neat but obviously doesn't constitute an academic reference: https://en.wikipedia.org/wiki/Hyperbola#The_tangent_bisects_the_angle_between_the_lines_to_the_foci

Does anybody know of any books or papers which use the same proof?