Assertion: electron's number | /r/CapableOf | grow to current six
Facets:
value: in 1973
type: TEMPORAL
Source sentences:
text: The number of supposed quark flavors grew to the current six in 1973, when Makoto Kobayashi and Toshihide Maskawa noted that the experimental observation of CP violation[nb 3] could be explained if there were another pair of quarks.