He-4  search
BTisotopes
 .stable isotopes
 ..He-4
BTnoble gases
 .helium
 ..He-4
RTHe-4/He-3
SNThis term has multiple hierarchies.
He-4/He-3  search
BTisotopes
 .stable isotopes
 ..He-4/He-3
BTnoble gases
 .helium
 ..He-4/He-3
UFHe-3/He-4
RTabsolute age
 isotope ratios
 He-3
 He-4
SNIsotopic ratio. As of 1989, use He/He for age determination method. This term has multiple hierarchies.