Google users can choose the "+" at the bottom of the calendar above.
iPhone support:
1. Settings
2. Mail, Contacts Calendars
3. Add Account
4. Other
5. Add Subscribed Calendar
6. server url: paste in this address.
https://calendar.google.com/calendar/ical/e8gltnfk5atddnkpu4jt34buq4%40group.calendar.google.com/public/basic.ics
iPhone support:
1. Settings
2. Mail, Contacts Calendars
3. Add Account
4. Other
5. Add Subscribed Calendar
6. server url: paste in this address.
https://calendar.google.com/calendar/ical/e8gltnfk5atddnkpu4jt34buq4%40group.calendar.google.com/public/basic.ics