Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
va thanh » gia thanh, va tinh, le thanh
tu sach » thu sach, su sach, te sach
ve chao » ve chat, ve cham, ve cho
tai cua » thai cua, tai cuc, tri cua
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
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: tu sach ty ((nang ma) or (nang x)) hoi. hieu ve chao xu ((va thanh) OR (ban thanh)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang ma) OR (nang x)) hoi. hieu ve chao xu ((va thanh) OR (ban thanh)) tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang ma) or (nang x)) hoi. hieu ve chao xu ((va thanh) OR (ban thanh)) tai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang ma) or (nang x)) hoi. hieu ve chao xu ((va thanh) OR (ban thanh)) tai cua tre*.