JJIF has a Google Kalendar

You can import and add this to your personal calendar

Link for feed reader:
https://www.google.com/calendar/feeds/g3f7f7ad10khv4n10t9m4u6rrc%40group.calendar.google.com/public/basic

Link for outlook and other iCal Systems:
https://www.google.com/calendar/ical/g3f7f7ad10khv4n10t9m4u6rrc%40group.calendar.google.com/public/basic.ics

Link for every webbroswer:
https://www.google.com/calendar/embed?src=g3f7f7ad10khv4n10t9m4u6rrc%40group.calendar.google.com&ctz=Europe/Berlin