Abdulrahim, K., C. Hide, T. Moore, and C. Hill. “Increased Error Observability of an Inertial Pedestrian Navigation System by Rotating IMU”. Journal of Engineering and Technological Sciences, vol. 46, no. 2, July 2014, pp. 211-25, doi:10.5614/j.eng.technol.sci.2014.46.2.7.