The doctrine of triangles a history of modern trigonometry por Van Brummelen, Glen

Available for University of the Philippines Diliman via IEEE Xplore. Click here to access
Also available remotely for University of the Philippines Diliman via IEEE Xplore. Click here to access thru EZproxy

Schaum's outline of precalculus por Safier, Fred

Available for University of the Philippines Diliman via McGraw-Hill Access Engineering. Click here to access
Also available remotely for University of the Philippines Diliman via McGraw-Hill Access Engineering. Click here to access thru EZproxy

Algebra and trigonometry por Sullivan, Michael

Three-way journal writing effects on students' problem-solving and self-regulation skills in trigonometry por Lugtu, Ivy C.

Precalculus functions and graphs por Swokowski, Earl William 1926-, Cole, Jeffery A. (Jeffery Alan) 1955-

Precalculus functions & graphs por Swokowski, Earl W.

Schaum's outline of trigonometry por Moyer, Robert, Ayres, Frank 1901-1994

Available for University of the Philippines Diliman via McGraw-Hill Access Engineering. Click here to access
Also available remotely for University of the Philippines Diliman via McGraw-Hill Access Engineering. Click here to access thru EZproxy

The fractional trigonometry with applications to fractional differential equations and science por Lorenzo, Carl F., Hartley, Tom T.

A basic approach to precalculus trigonometry preparing to succeed in calculus por Kim, Young H., Kim, Youngsoo, Tameru, Ana, Yan, Wen

Plane & spherical trigonomerty a tetrahedron approach por Mamhot, Millard R., Endam, Joemar C., Mamhot, Alice A., Banagua, Emelyn C., Bantug, Jenette S.