Perhaps you should try some spelling variations:
su sach » so sach, vu sach
lam cua » nam cua, lam chat
va danh » va dinh, va dan, dia danh
va hanh » van hanh, va thanh, ban hanh
vu pham » su pham, vi pham, vu kham
hieu vu » hieu va, hieu ve, hieu su
sach ty » sach y, sach tu, sach thu
tang ma » tang van
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: su sach ty ((tang ma) or (mang may)) hoi. hieu vu pham duc ((va hanh) OR (va danh)) lam cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((tang ma) OR (mang may)) hoi. hieu vu pham duc ((va hanh) OR (va danh)) lam cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((tang ma) or (mang may)) hoi. hieu vu pham duc ((va hanh) OR (va danh)) lam cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty ((tang ma) or (mang may)) hoi. hieu vu pham duc ((va hanh) OR (va danh)) lam cua tre*.