you can use table alias for this
Select ILLITM,ILDOC, ILDCT, ILTRDJ
FROM CRPDTA.F4111 tab1
where tab1.ILTRDJ in (Select max(tab2.ILTRDJ) FROM CRPDTA.F4111 tab2);
or if you are using this query inside any PL-SQL block , you can use a variable to hold max(ILTRDJ) and then use this variable in query.
You need to link the item in the primary query with the max in the subquery.
Assuming that ILLITM is the item than the query would be like this:
select X.ILLITM, X.ILDOC, X.ILDCT, X.ILTRDJ from CRPDTA.F4111 X where X.ILTRDJ in (select max(ILTRDJ) from CRPDTA.F4111 Y where Y.ILLITM = X.ILLITM);