If no date of distribution, release, broadcast, copyright, or production can be determined, give an approximate date enclosed in brackets.  If necessary, give an explanation in a note.  See 7B11.

Probable date

[1969]

Questionable date

[1916?]

Approximate date

[ca. 1960]

One year or another

[1971 or 1972]

Span of dates
    (Only for dates fewer than twenty years apart)

[between 1906 and 1912]

Probable decade

[192-]

Questionable decade

[192-?]

See also:

4E.  Dates of distribution, release, broadcast

4.  Distribution, Release, Broadcast Area