I am quite new to the field of category theory and I am searching for a good citation for the following statement in nLab (https://ncatlab.org/nlab/show/small+category):
"A category is said to be essentially small if it is equivalent to a small category. Assuming the axiom of choice, this is the same as saying that it has a small skeleton, or equivalently that it is locally small and has a small number of isomorphism classes of objects."
Any suggestions are welcome!