ASP.NET Calendar - Airline tickets

Departing date
    Select date
 
2014
2015
2016
2017
2018
2019
2020
 

Returning date
    Select date
 
2014
2015
2016
2017
2018
2019
2020
 

Notice that Returning date cannot be earlier than Departing date.

This validation happens automatically by calendar.

ASP.NET

<obout:Calendar runat="server"
                         id="startCal">
</obout:Calendar>


<obout:Calendar runat="server"
                         BeginDateCalendarId="startCal">
</obout:Calendar>