Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
van cam » van nam, van lam, van cau
hanh di » hanh de, hang di, danh di
y nang » ky nang, ly nang, v nang
xac va » tac va, ac va, bac va
tuc va » thuc va, truc va, tuc xa
x hoi » xa hoi, o hoi, x ho

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 y nang x hoi. hieu van cam ((xac va) or (tuc va)) ((hanh di) OR (hanh vi)) cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang x hoi. hieu van cam ((xac va) OR (tuc va)) ((hanh di) OR (hanh vi)) cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang x hoi. hieu van cam ((xac va) or (tuc va)) ((hanh di) OR (hanh vi)) cua vat".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang x hoi. hieu van cam ((xac va) or (tuc va)) ((hanh di) OR (hanh vi)) cua vat*.