Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
ve thanh » le thanh, de thanh, den thanh
so sach » so sanh, bo sach, co sach
ve chat » va chat, van chat
ve cham » va cham, vu cham, ve chim
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
mang xa » lang xa, mang may, dang xay
cua tre » cua te, cuu tre, cua triet
cuu ve » cuu va

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 ((mang xa) or (nang ma)) hoi. hieu ((ve cham) OR (ve chat)) cuu ve thanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty ((mang xa) OR (nang ma)) hoi. hieu ((ve cham) OR (ve chat)) cuu ve thanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty ((mang xa) or (nang ma)) hoi. hieu ((ve cham) OR (ve chat)) cuu ve thanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ty ((mang xa) or (nang ma)) hoi. hieu ((ve cham) OR (ve chat)) cuu ve thanh dai cua tre*.