Consistency: "Buses" vs "Busses"

While the dictionary says "busses" and "buses" are both valid plural forms of the word "bus", there are inconsistencies in spelling in the e-book (all Volume IV).

I've seen the word "busses" used in the following places:

* Titles Networks and busses and Short-distance busses - http://www.allaboutcircuits.com/vol_4/chpt_14/2.html

* In the microprocessor diagram in Microprocessors - http://www.allaboutcircuits.com/vol_4/chpt_16/4.html


And "buses" used in the following places:

* Inside Networks and busses in the paragraph above the Short-distance busses section and on the PCMCIA line in Short-distance busses (following the link above)

* In the 5th paragraph of Microprocessors linked to above

* The first word in Data flow - http://www.allaboutcircuits.com/vol_4/chpt_14/3.html


It looks like these are the only appearances judging by a quick search of the e-book, although it's possible I missed something.

Cheers,
Kris Katterjohn