1. AUTY, Fiona, et. al. Beginner's Guide to Measurement in Mechanical Engineering, NPL, London, online: http://www.npl.co.uk/upload/pdf/beg-guide-measurement-mech-eng.pdf
2. AUTY, Fiona, et. al. Beginner's Guide to Measurement in Electronic and Electrical Engineering, online: http://www.npl.co.uk/upload/pdf/gpg-132-beg-guide-measurement-electronic-electrical-eng.pdf