Perhaps you should try some spelling variations:
va tieng » va tinh, tu tieng, va thong
vat hanh » vat thanh, van hanh, va hanh
nam thuc » nam thuoc, am thuc, nam thu
sach ly » sach y, sach lo, sach ty
hanh va » hang va, hanh vi
hieu ve » hieu va, hieu van
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
mang xa » lang xa, mang may, dang xay
ve nam » he nam, va nam, le nam
thiet » thieu

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 ly ((mang xa) or (nang ma)) hoi. hieu ve nam thuc vat hanh va ((va tieng) or (va thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ly ((mang xa) OR (nang ma)) hoi. hieu ve nam thuc vat hanh va ((va tieng) OR (va thiet)).
• Adding a wildcard symbol may retrieve word variants: su sach ly ((mang xa) or (nang ma)) hoi. hieu ve nam thuc vat hanh va ((va tieng) or (va thiet))*.