Dates: 1905-1987.

If a majority of the records come from a certain period, it is acceptable to make a note of the "predominant" dates, as in:

Dates: 1905-1987 ; predominant 1932-1987.

If there are only one or two records outside the predominant date range, list them individually:

Dates: 1905, 1932-1987.

If there is a long gap between two distinct sets of date ranges list them like this:

Dates: 1905-1932 ; 1944-1987

Note: Sometimes exact dates will not be known. Although it is common practice to indicate this by writing "n.d." ("no date") in cases like this it is preferable to estimate probable or uncertain dates. The conventions which will be most commonly used for estimating dates are:

Probable date: [1867?]
Approximate date: [ca. 1975]
Decade certain: [197-]
Probable decade: [197-?]

So...given all of the above, the Date element of a RAD description could look something like this:

Dates: 1895, 1910-1921, 1947 - [197-?] ; predominant 1951-1965.

19 times out of 20, however, it will look like this: