Perhaps you should try some spelling variations:
duong hoi » duong loi, dong hoi, duong noi
muong hoi » muong hoa, truong hoi, luong hoai
hieu van » hieu va, thien van, lieu va
van lam » van nam
lam tuc » lam thuoc, lam truoc, luat tuc
bo sach » co sach, hoc sach
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: bo sach ty ((nang xa) OR (nang ma)) hoi. hieu van lam tuc xa ((muong hoi) or (duong hoi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: bo sach ty ((nang xa) OR (nang ma)) hoi. hieu van lam tuc xa ((muong hoi) OR (duong hoi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "bo sach ty ((nang xa) OR (nang ma)) hoi. hieu van lam tuc xa ((muong hoi) or (duong hoi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: bo sach ty ((nang xa) OR (nang ma)) hoi. hieu van lam tuc xa ((muong hoi) or (duong hoi)) cua tre*.