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
cua tre » cua te, cuu tre, cua triet
ve cam » ve cham, ve cac, ve cai
va cam » va cham, va cac, va cao
luc va » duc va, tuc va, loc va
vi cua » vai cua, di cua

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