Mass in general relativity Robert Geroch Section 6.2 in Szabados, László B. (2009), "Quasi-Local Energy-Momentum and Angular Momentum in GR", Living Rev. Relativ.
رابرت جروچ جرم در نسبیت عام بخش 6.2 درSzabados, László B. (2009), "Quasi-Local Energy-Momentum and Angular Momentum in GR", Living Rev. Relativity