Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
nang xa » nang x, lang xa, nang ma
van cac » van hac, van cau, van bac
truc va » thuc va, thuc vat, trung va
tai cua » thai cua, tai cuc, dai cua
y nang » ky nang, ly nang, v nang

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach y nang xa hoi. hieu van cac ((duc va) or (truc va)) hanh ((tai cua) OR (tri cua)) viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang xa hoi. hieu van cac ((duc va) OR (truc va)) hanh ((tai cua) OR (tri cua)) viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang xa hoi. hieu van cac ((duc va) or (truc va)) hanh ((tai cua) OR (tri cua)) viet".
• Adding a wildcard symbol may retrieve word variants: su sach y nang xa hoi. hieu van cac ((duc va) or (truc va)) hanh ((tai cua) OR (tri cua)) viet*.