leap year:

More on leap year from Fact Monster:

• Leap Year 101 - All about leap year|Why and when we have leap years
• Leap Year Explained - 2008 is no common year
• calendar - calendar calendar [Lat., from Kalends], system of reckoning time for the practical purpose of ...
• Calendars: Holidays, seasons, religious calendars, leap year, and daylight saving time - Calendar information, including ancient and religious calendars, major holidays, time zones, birthstones, astrological signs, hours, names, sundials, water clocks, and more.
• Measuring Years - Measuring Years The word for the longest measurement of time is kalpa, Hindi for 432 billion years. ...

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