- Strasser, G. J. & Schwendener, H. R., “A North-seeking gyro attachment for the theodolite”, Bulletin Géodésique, No. 79, March 1966.
- Schwendener, H. R. & Ward, A. H., “The gyroscopic attachment as a convenient instrument for determining azimuth”, Wild Heerbrugg Publication, c. 1967.
- Sutton, D. & Thomas, T. L., “New meridian indicator for the precise determination of underground azimuths”, Trans. Institution of Mining and Metallurgy, London, 73, 1, Oct. 1963.
- Thomas, T. L., “Precision indication of the meridian”, The Chartered Surveyor, March 1965.
- Thomas, T. L., “The precision indicator of the meridian: Theory and application”, Proc. Third South African Survey Conference, Johannesburg, Jan. 1967.
- Bomford, G., Geodesy, 3rd. edition. Oxford University Press: Clarendon Press, 1971.
Survey Review
Volume 21, 1971 - Issue 161