Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
tai cua » thai cua, tai cuc, tri cua
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
ve choi » ve thoi, ve cho, ve khoi
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
xu van » tu van, vu van, su van
xu va » tu va, su va, vu va

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 choi ((xu va) OR (xu van)) doanh 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 choi ((xu va) OR (xu van)) doanh 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 choi ((xu va) OR (xu van)) doanh tai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang ma) or (nang x)) hoi. hieu ve choi ((xu va) OR (xu van)) doanh tai cua tre*.