How to subscribe to a shared google calender?

There are two calenders shared with my google account. I want this calenders to appear on my iPhone, however I can't manage to do that. What I tried sofar:

1) I added my Google Account to my devices and made sure that the calendar is synced. This worked as I can access my own calendars. Additionaly one of the shared calendars are synced, but I don't find any way to sync the second calendar. Is syncing limited to only one shared calendar?!?

2) I tryed to to add the calender using the public ical address. But this fails as I keep receiving a "Unable to verify account information" and "Cannot Connect Using SSL. Do you want to try setting up the account without SSL?". I tried setting up the account with and without SSL but both fail.