'Quantities and units' (Materials, Circuits and Devices, 2019), 'Understandable Electric Circuits: Key concepts', 2nd ed., Chap. r, pp. 1-13, DOI: 10.1049/PBCS047E_chr
IET Digital Library, https://digital-library.theiet.org/;jsessionid=5bmsl7q6h3u51.x-iet-live-01content/books/10.1049/pbcs047e_chr