The following example search for files containing the strings AA and DD :
$ more f?.txt
::::::::::::::
f1.txt
::::::::::::::
AA
BB
CC
DD
::::::::::::::
f2.txt
::::::::::::::
AA
BB
CC
::::::::::::::
f3.txt
::::::::::::::
BB
CC
DD
::::::::::::::
f4.txt
::::::::::::::
BB
CC
$ grep -l AA $(grep -l DD f?.txt) /dev/null
f1.txt
$