Zhegalkin polynomial Boolean algebra

Question

I have to find the Zhegalkin polynomial of $ (x\rightarrow y)\rightarrow z $. Please tell me if this is right: my polynomial is of this kind $ a_{0} + a_{1}x + a_{2}y + a_{3}z + a_{4}xy + a_{5}yz + a_{6}xz + a_{7}xyz $ , I then make a truth table and from the values of that truth table i find the coefficients $a_{0},a_{1}...$ I also want to ask if I have something more complex as a statement is it useful to use equivalence transitions and can I get the Zhegalkin polynomial using only equivalence transitions ? Thanks in advance.