When citing a reference within a reference i.e. another author’s work referred to in material being read.
Direct reference:
Research recently carried out in the Greater Manchester area by Brown (1966 cited by Bassett 1986, p.142) found that …
Indirect reference:
(Brown, 1966 cited by Bassett, 1986, p.142)
Above example shows that Brown carried out the work being referred too but which has not been read directly. Instead, Bassett is secondary source providing summary of Brown’s work.