select distinct
       d_month,
       d_week
from (-- months and weeks for every day in a year
      select
        datum d_date,
        to_char(datum, 'mm') d_month,
        to_char(datum, 'ww') d_week
      from (-- all days within the current year
            select
            trunc(sysdate, 'yyyy') + level - 1 datum
            from dual
            connect by level <= add_months(trunc(sysdate, 'yyyy'), 12)
                              - trunc(sysdate, 'yyyy')
           )
     )
order by d_month, d_week;

M  W
-- --
01 01
01 02
01 03
01 04
01 05  --> the 5th week belongs to both Jan and Feb.
02 05  --> Where would you like to put it?
02 06
02 07
02 08