I came to the note: $$ X(z)= \sum_{}^{} \frac{N(s)} {D'(s)} * \frac {z} {z - e ^ {Ts}}.at.s=sp $$
But in the textbook it's written in the form $$ X(z)= \sum_{}^{} {residue.of \frac {X(z) z} {z - e ^ {Ts}}.at.s=sp} $$
where N(s) and D(s) are the numerator and denominator of the X(s)
So which one is right?