Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
hieu ve » hieu va, hieu van
nang xa » nang x, lang xa, nang ma
luc va » duc va, loc va
ve cau » ke cau, va cau, ve cac
tuc va » thuc va, truc va, tuc xa

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