Raman, Rahul; Sa, Pankaj K.; Majhi, Banshidhar; Bakshi, Sambit: 'Fusion of shape and texture features for lip biometry in mobile devices' (Security, 2017), 'Mobile Biometrics', Chap. 6, pp. 155-176, DOI: 10.1049/PBSE003E_ch6
IET Digital Library, https://digital-library.theiet.org/;jsessionid=1akokttkc3gaq.x-iet-live-01content/books/10.1049/pbse003e_ch6