I learn an article the place it’s sayed: $E_1(mathbb{Q}_p)approx mathbb{Z}_p$

the place $E$ is an elliptic curve over $mathbb{Q}_p$ and $E_1(mathbb{Q}_p)={Pin E(mathbb{Q}_p):tilde{P}=tilde{O}}$.

The writer says that the proof is in “Arithmetic of elliptic curves” by J.Silverman, at web page 191, however right here it’s sayed:

If $E$ is an elliptic curve over $mathbb{Q}_p$ and $hat{E}$ is the formal group, then:

$$E_1(mathbb{Q}_p)approx hat{E}(pmathbb{Z}_p)$$

So i dont know a superb reference for the proof of $E_1(mathbb{Q}_p)approx mathbb{Z}_p$.