Return only the row where the date in one column is closest to the date in another column?

I'm working on a query but it's returning some duplicate values and I need to return only the row where the date in one column is closest to the date in another column.

My query looks something like this:

SELECT p.Id, r.ReferralDate, s.SupervisionDate
FROM person p
INNER JOIN referral r on r.PersonId = p.Id
INNER JOIN supervision s on s.PersonId = p.Id



Which returns something like this:

Id Supervision Date Referral Date
123 2015-09-30 2015-08-30
123 2020-02-30 2015-08-30
123 2020-06-30 2015-08-30

How can I write a query that returns the Supervision Date that is closest to the Referral Date? So that the final output looks like this:

Id Supervision Date Referral Date
123 2015-09-30 2015-08-30

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