What are the Six Breweries allowed to serve Octoberfest Beer in Munich?

I am looking for the six breweries allowed to serve Oktoberfest beer in during the festival in Munich Germany.

I am told there is only six that are allowed and that follow the strict Reinheitsgebot Purity Laws.  Some help is greatly appreciated.

Thank you forum

Googled this in German and here is your answer: http://www.oktoberfest.de/de/article/Das+Oktoberfest/Bier/Die+sechs+Münchner+Brauereien/1686/

Cool, I got 5 out of 6 right!  Missed Lowenbrau (I guessed Ayinger).

I missed Lowenbrau too, but I thought there were only five breweries.

Of those 6-
Hacker-Pschorr is owned by Paulaner. 49% of Paulaner is owned by Heineken.

Löwenbräu was bought by Spaten. Spaten was bought by InBev, now ABInbev.

Hofbräuhaus is the state owned brewery.

Augustiner is still independent.