Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
doan vi » doan va, don vi, doan thi
cua tre » cuu tre, cua triet, dua tren
ve cac » va cac, vien cac
cac tu » cac thu, cach tu, cac du
dan vi » don vi, dan va, gan vi
cua te » cua tu

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 ky nang xa hoi. hieu ve cac tu va ((dan vi) or (doan vi)) ((cua tre) OR (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang xa hoi. hieu ve cac tu va ((dan vi) OR (doan vi)) ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang xa hoi. hieu ve cac tu va ((dan vi) or (doan vi)) ((cua tre) OR (cua te))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang xa hoi. hieu ve cac tu va ((dan vi) or (doan vi)) ((cua tre) OR (cua te))*.