Link to add calendar to google (android) -

https://calendar.google.com/calendar/u/0?cid=YTNwdTBhazk5bWUzN2Y3YThqbjFnMWdhdDRAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ

Link to add calendar to iCal(apple) -

https://calendar.google.com/calendar/ical/a3pu0ak99me37f7a8jn1g1gat4%40group.calendar.google.com/public/basic.ics