IODP SEDIS - Thesaurus -

He-4/He-3
BT	isotopes
	.stable isotopes
	..He-4/He-3
BT	noble gases
	.helium
	..He-4/He-3
UF	He-3/He-4
RT	absolute age
	isotope ratios
	He-3
	He-4
SN	Isotopic ratio. As of 1989, use He/He for age determination method. This term has multiple hierarchies.