dsEventCalendar Pro support Google Calendar.

You must first have a Google Calendar API Key:

1. Go to the Google Developer Console and create a new project (it might take a second).
2. Once in the project, go to APIs & auth > APIs on the sidebar.'
3. Find "Calendar API" in the list and turn it ON.
4. On the sidebar, click APIs & auth > Credentials.'
5. In the "Public API access" section, click "Create new Key".
6. Choose "Browser key".'
7. If you know what domains will host your calendar, enter them into the box. Otherwise, leave it blank. You can always change it later.
8. Your new API key will appear. It might take second or two before it starts working.'

 
Make your Google Calendar public:

1. In the Google Calendar interface, locate the "My calendars" area on the left.
2. Hover over the calendar you need and click the downward arrow.'
3. A menu will appear. Click "Share this Calendar".
4. Check "Make this calendar public".'
5. Make sure "Share only my free/busy information" is unchecked.
6. Click "Save".'

 Obtain your Google Calendar's ID:

1. In the Google Calendar interface, locate the "My calendars" area on the left.'
2. Hover over the calendar you need and click the downward arrow.
3. A menu will appear. Click "Calendar settings".'
4. In the "Calendar Address" section of the screen, you will see your Calendar ID. It will look something like "abcd1234@group.calendar.google.com".