For the page, in this month children do not pay up to 10 children for free only for October and we buy it through the San Diego zoo page.
Actually it takes you nothing to buy them at the entrance, and I don't know, if they make you valid online that children under 11 this month do not pay :)
You can on the sandiegozoo page ... although in the same entrance of the zoo it is quite fast and you can choose several options easily
https://zoo.sandiegozoo.org/tickets
Youtube.com/sdzoo
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