Comrade Cao is right. I also would like to point out something else. The Z as in "zoo" pronunciation for the Vietnamese "gi-" is from the northern dialect (our audio guy). The south pronounces the "gi-" as a Y sound as in "yes".
Is that from the International Phonetic Alphabet? I'm sorry, I'm not familiar with it =( Regardless, the V in Vietnamese makes an English V sound as in "vacuum" in the northern dialect, and a Y sound as in "yes" in the south.
Thanks for educating me! I'm from Canada so the Vietnamese dialects I typically hear are north and south. Of course, there are many other dialects in between. I might have heard the V pronounced like that before.