Scheduling and managing events using Outlook.com calendar
You may refer to an answered query about Office .ics format by jriver27 dated April 11, 2017. Here is the link to redirect you to his answer.
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Elmer San: Thanks again for trying to solve my problem. I checked out the link for the work around that was listed. Unfortunately it as not a solution for me. Given the time involved in trying the many "work-arounds" I'd tried, I decided to cut the process short and hand code the several years of info into my calendars that couldn't be exported as an ICS file. It would appear that there is no direct way of exporting multiple years of a Calendar out of Outlook.com Perhaps that feature will be an element in some future build of Outlook.com Thanks for the effort, I appreciate it.