1. ISO 1101:2017, Geometrical product specifications (GPS) — Geometrical tolerancing — Tolerances of form, orientation, location and run-out, ISO, Geneva.
2. SI unit brochure - 9th edition, BIPM, France, 2019.
3. IS 6231: Prismatic Angle Gauges (1998), Bureau of Indian Standards (BIS), India.
4. P.C. Jain, Weights, Measures & Dimensional Metrology, Techniques for Calibration of Angle Standards, A Pragati Publication, 1997. ISBN-81-755-076-2.
5. Wayne R. Moore, Foundations of mechanical accuracy, The Moore Special Tool Company 1970, USA.