Perhaps you should try some spelling variations:
tru nang » tri nang, truc nano, thi nang
tra nang » thi nang, kha nang, da nang
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
van cao » van dao, van bao, van hao
cao duc » dao duc, cao suc, giao duc
va dan » ca dan, va dao, va dau
cua tu » cua tuc, cua su, cua cu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((tru nang) or (tra nang)) xa hoi. hieu van cao duc va dan ca ((cua te) OR (cua tu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((tru nang) OR (tra nang)) xa hoi. hieu van cao duc va dan ca ((cua te) OR (cua tu)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((tru nang) or (tra nang)) xa hoi. hieu van cao duc va dan ca ((cua te) OR (cua tu))".
• Adding a wildcard symbol may retrieve word variants: tu sach ((tru nang) or (tra nang)) xa hoi. hieu van cao duc va dan ca ((cua te) OR (cua tu))*.