Prokopets, V., Zdoryk, O. and Georgiyants, V. 2017. Development and standardization of test systems based on filter paper and modified with vanillin reagent. ScienceRise: Pharmaceutical Science. 4 (8) (Aug. 2017), 46–50. DOI:https://doi.org/10.15587/2519-4852.2017.109254.