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103 trigonometry problems: from the training of the USA IMO team
Author(s): Titu Andreescu, Zuming Feng
 Trigonometry Demystified
Author(s): Stan Gibilisco
Plane Trigonometry
Author(s): E. Richard Heineman, J. Dalton Tarwater
Elements Of Plane Trigonometry
Author(s): Robert E. Moritz

Schaum’s Outline of Trigonometry 3rd Edition
Author(s): Robert E. Moyer, Frank Ayres
Essentials of plane trigonometry and analytic geometry
Author(s): Antherton H. Sprague
Algebra and Trigonometry 3rd Edition
Author(s): Judith A. Beecher, Judith A. Penna, Marvin L. Bittinger
Teach Yourself Trigonometry
Author(s): P. Abbott, M.E. Wardle

Trigonometry. Cliffs Quick Review
Author(s): David A. Kay
Trigonometry 6th Edition
Author(s): Charles P.(Charles P. McKeague) McKeague, Mark D. Turner
Schaum’s Outlines Trigonometry 4th Edition
Author(s): Moyer Robert E., Ayres Frank
Precalculus with Trigonometry – Concepts and Applications
Author(s): Paul A . Foerster