The Oregon Tax Court noted that both parties cite Distinguished Research Professor & Shackelford Distinguished Professor in Taxation Law Emeritus Walter Hellerstein's State Taxation, "a leading treatise on state taxation" and quotes the treatise "[f]or a discussion of the line-drawing problems in the imposition of sales and use taxes within the chain of consumption," in Ean Holdings, LLC v. Department of Revenue (August 12, 2020).