In a paper I am reading, the author states:
"It is simple and well known that a graph of girth $g$ and $q$ vertices has at most $q^{1+(O(1)/g)}$ edges"
He says that a proof can be found on Extremal Graph Theory, by Bela Bollobas.
However, I do not have easy access to that book.
Could someone please direct me to a more common graph theory book that has this result or some equivalent result?