What is the local maximum and minimum values and saddle point(s) of the function?

f(x,y) =x³-27xy+27y³

maximum

f(,) =(smallerxvalue)

f(,) =(largerxvalue)

minimum

f(,) =(smallerxvalue)

f(,) =(largerxvalue)

saddle points

(,) (smallestxvalue)

(,) (largestxvalue)