Harpen, N. H. v., & Watkins, S. J. (1930). The electrometric determination of the hydrogen ion concentration in the latex of Hevea brasiliensis and its applicability to technical problems. Varekamp & Co.
Lua i Stíl Chicago (17ú heag.)Harpen, Nicolaas Hendrik van, agus S. J. Watkins. The Electrometric Determination of the Hydrogen Ion Concentration in the Latex of Hevea Brasiliensis and Its Applicability to Technical Problems. Medan: Varekamp & Co, 1930.
Lua MLA (8ú heag.)Harpen, Nicolaas Hendrik van, agus S. J. Watkins. The Electrometric Determination of the Hydrogen Ion Concentration in the Latex of Hevea Brasiliensis and Its Applicability to Technical Problems. Varekamp & Co, 1930.
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