# Calendar Data Sources

Source: [https://docs.virtosoftware.com/docs/calendar-overlay-pro/data-sources/calendar-data-sources/](https://docs.virtosoftware.com/docs/calendar-overlay-pro/data-sources/calendar-data-sources/)


Here, you can find detailed information about calendars and data sources that you can overlay in Virto Calendar App for SharePoint.

With Virto Calendar App, you can overlay various calendars in a single calendar view. Let’s see which calendars you can use as data sources.

You can create an unlimited number of calendars with multiple data sources.

[Watch the video](https://www.youtube.com/watch?v=gNaGi28d-cQ)

## Exchange Online calendars

With Virto Calendar App, you can combine any number of [**Exchange Online shared and personal calendars**](/docs/calendar-overlay-pro/data-sources/overlay-exchange-calendars-outlook-calendars) into a single calendar. This is the fastest way to create a calendar overlay because no special fine-tuning is required for this data source.

## Resource calendars

If you use a shared mailbox to book [**resources in SharePoint**](/docs/calendar-overlay-pro/data-sources/meeting-rooms), you can add it to the Virto Calendar App to track meeting rooms, equipment and other resources in a single place.

## SharePoint lists

It is one of the most popular options for overlaying calendars. Use [**SharePoint lists**](/docs/calendar-overlay-pro/data-sources/sharepoint-list-as-a-data-source)(including lists in a calendar view) as data sources for your overlay. You can overlay an unlimited number of lists in a single view.

## Microsoft Planner

Do you have [**tasks in Microsoft Planner**](/docs/calendar-overlay-pro/data-sources/microsoft-planner)? Add these to your Virto Calendar App, too.

## Public folders

Public folders in SharePoint are designed for shared access. Since every [**public folder**](/docs/calendar-overlay-pro/data-sources/public-folders) has a mailbox, it can be easily added to a Virto calendar as a data source.

## Internet calendars (iCal feeds)

An iCalendar or .ics feed isa unique calendar format for most calendar solutions. Generate iCal links and [**overlay events from Google Calendar**](/docs/calendar-overlay-pro/data-sources/internet-calendars-icalendar-feed-google-calendar) or any other external calendar that supports iCalendar feeds.