In "Volume IV - Digital | Logic Gates | The NOT Gate", about halfway down, there seems to be a grammatical error. The word "of" should be "if". The phrase is correct in the next paragraph.

The astute observer will note that this inverter circuit's input will assume a "high" state of left floating (not connected to either Vcc or ground).

Should be:

The astute observer will note that this inverter circuit's input will assume a "high" state if left floating (not connected to either Vcc or ground).

P.S. Like the new e-book format on my smartphone.

 

Verified. Thanks for the correction!