US 1506316, "Pyrazolone dye and process of making the same"
rsc.org
Barnard, John M. (28 Oct 2009). "Markush Structure Searching"(PDF). Royal Society of Chemistry www.rsc.org. Archived from the original(PDF) on 2015-12-22. Retrieved 15 Jan 2014.
Barnard, John M. (28 Oct 2009). "Markush Structure Searching"(PDF). Royal Society of Chemistry www.rsc.org. Archived from the original(PDF) on 2015-12-22. Retrieved 15 Jan 2014.