Subscribing to a Master Calendar using Google Calendar
In Master Calendar, click Notifications/iCal Feeds
Select at least one calendar and click the right arrow. In the screenshot below, I am subscribing to three different calendars at once.
When you are satisfied with your calendar selection, click iCalendar Feed
Select the Http iCal Link and copy it to your clipboard
In your Google calendar, click the down arrow next to Other Calendars and select Add by URL
Paste the iCal URL into the URL field and then click Add Calendar