Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
cuu tre » cua tre, cau tren, cau treo
dao voi » da voi, dao noi, do voi
ca tren » cau tren, cu tren, la tren
hieu ve » hieu va, hieu van
ty nang » ty xang, ty hang, ly nang
ve cac » va cac, vien cac
va dao » ca dao
cac su » cach su, cac sau, cac du
o hai » co hai, so hai, o lai
su va » su van, tu 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) or (ky nang)) o hai. hieu ve cac su va dao voi ((cuu tre) or (ca tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ty nang) OR (ky nang)) o hai. hieu ve cac su va dao voi ((cuu tre) OR (ca tren)).
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty nang) or (ky nang)) o hai. hieu ve cac su va dao voi ((cuu tre) or (ca tren))*.