I already went through that discussion with Gram. Google both terms and see which comes up with most apt results? "Butterfly Cut" gives jack-all. (lol, jackall)
edit: Not to mention the term that different saga's use translates to Blood Eagle, and makes no mention whatsoever of butterflies.
I find your year 9 social studies book just as, if not moreso questionable and biased than Wikipedia. Especially given that it has no outside input.