Perhaps you should try some spelling variations:
so sach » so sanh, bo sach, co sach
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
tieu su » thieu so
sach ty » sach y, sach tu, sach thu
hieu su » hieu sau, hieu so, hieu suat
tang ma » tang van
cua tre » cua te, cuu tre, cua triet
va cua » va chua, via cua, ca cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ty ((tang ma) or (mang may)) hoi. ((hieu su) or (tieu su)) pham duc va hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty ((tang ma) OR (mang may)) hoi. ((hieu su) OR (tieu su)) pham duc va hanh va cua tre.
• Adding a wildcard symbol may retrieve word variants: so sach ty ((tang ma) or (mang may)) hoi. ((hieu su) or (tieu su)) pham duc va hanh va cua tre*.