^By definition of the "foot" as exactly 1/3 yards, and of the international yard as "exactly 0.9144 metres", and of the metre (SI unit) defined by the International Bureau of Weights and Measures as the "length of the path traveled by light in vacuum during a time interval of 1/299792458 of a second". The time taken by light to travel 1 foot in a vacuum is therefore (1/299792458)x(0.9144/3) seconds, or 1.016703362164 nanoseconds.
^"Official BIPM definition of the metre". BIPM. Archived from the original on 2003-10-29. Retrieved 2008-09-22.
^Philips Semiconductors. "74HC-T-U-User-Guide" (PDF). Archived (PDF) from the original on 2022-10-09.