Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
cua triet » cua viet, su triet, va triet
hieu van » hieu va, thien van, lieu va
dinh dai » sinh dai, dinh dao, dinh tai
dinh dat » dinh ket, dinh van, dinh lam
tang xa » trang xa, tang ma, lang xa
van cac » van hac, van cau, van bac
cac loc » cac lop, cac toc, cac hoc
cua tre » cua te, cuu tre, dua tren
y tang » ky tang, 6 tang, 7 tang
loc va » hoc va, luc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sach y tang xa hoi. hieu van cac loc va ((dinh dai) OR (dinh dat)) ((cua tre) or (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sach y tang xa hoi. hieu van cac loc va ((dinh dai) OR (dinh dat)) ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sach y tang xa hoi. hieu van cac loc va ((dinh dai) OR (dinh dat)) ((cua tre) or (cua triet))".
• Adding a wildcard symbol may retrieve word variants: thuat sach y tang xa hoi. hieu van cac loc va ((dinh dai) OR (dinh dat)) ((cua tre) or (cua triet))*.