Let us note (for later reference) that......
We quote for future reference another result of Fox: there exists......
For these considerations it will be convenient to state beforehand, for easy reference, the following variant of......
The best general reference <An excellent recent reference> for...... is [5].
At the time of writing [5], I was not aware of this reference.
Where it is possible, we outline the proofs so that the reader will not have to hunt for obscure references.
We have thus proved the theorem without any reference to integration.