# How to show the existence and uniqueness of the pullback connection in vector bundles?

There is the following result: If $D$ is a connection on a vector bundle $E$ over $N$ and $φ$ is a smooth map from $M$ to $N$, then there is a pullback connection on $φ^*E$ over M, determined uniquely by the condition that $(φ^*D)_X(φ^*s)=φ^*(D_{dφ(X)}s)$.

I want to know how to show the existence and uniqueness of the pullback connection. Can you show it to me or give some reference which discuss this point?

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