Page 70, top. Corrections in Eq. (3.64), (3.65) and related text:
with the constraint

$$\sum_{j=0}^{m} \langle \psi^{(j)} \vert \psi^{(m-j)} \rangle = 0, \; m \neq 0.$$ (3.64)

Here are collected all terms of order $\lambda^m$ and then $\lambda$ is set to $1$. Taking matrix elements of (3.63) leads to

$$\sum_{j=0}^{m} \sum_{k=0}^{m} \Theta(m-j-k) \langle \psi^{... ...{H}} - \varepsilon)^{(m-j-k)} \vert \psi^{(k)} \rangle = 0,$$ (3.65)

where $\Theta(p) = 1, \; p \geq 0; 0, \; p < 0$. The desired expressions can be derived by applying the condition that (3.65) be variational with respect to $\psi^{(k)}$ at each order $k = 0, \ldots, m$.