1. Ahlfors L. and Beurling A., “Conformal invariants and function-theoretic null-sets,” Acta Math., 83, No. 1/2, 101–129 (1964).
2. Fuglede B., “Extremal length and functional completion,” Acta Math., 98, No. 3–4, 171–219 (1957).
3. Shabat B. V., “The modulus method in space,” Dokl. Akad. Nauk SSSR, 130, No. 6, 1210–1213 (1960).
4. Reshetnyak Yu. G., Space Mappings with Bounded Distortion, Amer. Math. Soc., Providence (1989).
5. Poletskiĭ E. A., “The modulus method for nonhomeomorphic quasiconformal mappings,” Math. USSR-Sb., 12, No. 2, 260–270 (1970).