@article {Rekus:1958:0003-7028:141,
	author = "Rekus, Andrew F.",
	title = "The Spectrographic Determination of Potassium in Coal Ash",
	journal = "Applied Spectroscopy",
	volume = "12",
	number = "5",
	year = "1958",
	abstract = "Indium, which is relatively absent in coal, is described as the ideal internal standard for the determination of potassium in coal ash. The chemical composition of the coal ashes examined varied over considerable limits. The standard deviation was slightly less than % 6±. Indium is also suggested as a possible ideal internal standard for sodium determinations.",
	pages = "141-142",
	url = "http://www.ingentaconnect.com/content/sas/sas/1958/00000012/00000005/art00004",
	doi = "doi:10.1366/000370258774615320"
}