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2. Modern instrumental methods of elemental analysis of petroleum products and lubricants;Nadkarni,1991
3. Methodology for the determination of minor and trace elements in petroleum cokes by WD-XRF;Gazulla;X-ray Spectrom,2010
4. ASTM D5863-00a. Standard test methods for determination of nickel, vanadium, iron, and sodium un crude oils and residual fuels by flame atomic absorption spectrometry; 2011.
5. IP Standard Test Method 465/01(10). Liquid petroleum products – determination of nickel and vanadium content – atomic absorption spectrometric method.