How to group words in a calendar?

Calendar,

Historically,

Gregorian calendar,

History,

Experience,

Origin,

Lunar calendar,

Experience,

Imperial calendar,

Experience,

Travel,

Calendar,

Over the years,

The previous one,

Resume,

Hijri，

Calendar,

Medical records,

Tibetan calendar,

Education,

Qualifications,

Gregorian calendar,

Calendar,

Adventure,

Duration,

Continuous,

of course，

Western calendar,

Go through it,

Dynasties