8Jaitly V K, Jain P K. Estimation of trace of acid content of bitumen by potentiometic titrations. Bull Electrochem, 19862(2) :205-206
9Ryszard Heropolitaski, Aleksandra Oburska, Janusz Lamparski. A simplified method for determining the acidity of mineral oils. Nafta (Katowice, Pol), 1977, 33(6): 204-206
10Minkova Z A, Bebaev Ⅵ, Maslova O M. Potentiometric determination of acid numbers of colored products of paraffin oxidation. Khim Prom-st, Ser: Metody Anal. Kontrolga Kach Prod Khim Prom-sti, 1981, (3): 18-20