Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, hieu ve
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
thuc va » thuc vat, thuc dan, thuc day
tinh vi » trinh vi, tinh voi, tinh va
cua tre » cua te, cuu tre, cua triet
tuc va » truc va, tuc xa, duc va
vi cua » vai cua, di cua

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 ky nang xa hoi. ((hieu van) or (lieu va)) lam ((tuc va) OR (thuc va)) tinh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang xa hoi. ((hieu van) OR (lieu va)) lam ((tuc va) OR (thuc va)) tinh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang xa hoi. ((hieu van) or (lieu va)) lam ((tuc va) OR (thuc va)) tinh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang xa hoi. ((hieu van) or (lieu va)) lam ((tuc va) OR (thuc va)) tinh vi cua tre*.