To subscribe to any of the calendars in your personal logged-in Google account calendar, you can use the "+Google Calendar" button in the lower right corner of the calendar view above.
To subscribe to a calendar using other calendar applications, copy (e.g., using a right-click) an ics URL (e.g., from this a link like this IEEE 802 LMSC iCal subscription link)
and paste it into your application's URL subscription function. For example, see instructions for Outlook.