Definition of kilogram:
Inside was about a kilogram of strontium- 90; it would keep on emitting electrons for twenty- five years, normally, but there was a miniature plutonium reactor, itself shielded with collapsium, which, among other things, speeded that process up considerably.- "Four-Day Planet", Henry Beam Piper.
- "The Journal of Submarine Commander von Forstner", Georg-Günther von Forstner Commentator: John Hays, Jr. Hammond.
- "The Voyage of the Vega round Asia and Europe, Volume I and Volume II", A.E. Nordenskieold.