Stakhina L. D. The effect of EOR technologies on the content of petroporphyrins and naphthenic acids of recovered heavy oils from Usinskoye field / L. D. Stakhina, D. S. Petrenko, A. S. Spabekova // Key engineering materials. 2015. Vol. 670. P. 39-43. URL: http://vital.lib.tsu.ru/vital/access/manager/Repository/vtls:000569985