'Spread-spectrum transmission' (Telecommunications, 2017), 'Introduction to Digital Wireless Communications', Chap. 7, pp. 147-166, DOI: 10.1049/PBTE072E_ch7
IET Digital Library, https://digital-library.theiet.org/;jsessionid=45k6c1ad9c2q.x-iet-live-01content/books/10.1049/pbte072e_ch7