εισιτηρίων / εισιτηριών

Question

I sometimes see the genitive plural εισιτηριών, so with a final accent. Why is this? According to grammar, I would expect εισιτηρίων.

Here you can see some examples:

https://www.google.nl/search?q=%22%CE%B5%CE%B9%CF%83%CE%B9%CF%84%CE%B7%CF%81%CE%B9%E1%BD%BD%CE%BD%22&biw=1403&bih=667&ei=pP2dY-eeG5-W9u8PkOiNmA8&ved=0ahUKEwjngJr8l4H8AhUfi_0HHRB0A_M4ChDh1QMIDg&uact=5&oq=%22%CE%B5%CE%B9%CF%83%CE%B9%CF%84%CE%B7%CF%81%CE%B9%E1%BD%BD%CE%BD%22&gs_lcp=Cgxnd3Mtd2l6LXNlcnAQAzoKCAAQRxDWBBCwA0oECEEYAEoECEYYAFDVD1jYIGDXJGgBcAF4AIABfYgBxQGSAQMxLjGYAQCgAQHIAQjAAQE&sclient=gws-wiz-serp

Answer 1

This is incorrect in modern Greek, it could be a typing mistake:  "εισιτηριών"