Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
tu sach » thu sach, su sach, te sach
hieu vu » hieu va, hieu ve, hieu su
vu cham » va cham, vu kham, tu cham
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, tuc va, xac va
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) or (thuoc sach)) ky lang xa hoi. hieu vu cham ((xuc va) OR (luc va)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thuoc sach)) ky lang xa hoi. hieu vu cham ((xuc va) OR (luc va)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thuoc sach)) ky lang xa hoi. hieu vu cham ((xuc va) OR (luc va)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thuoc sach)) ky lang xa hoi. hieu vu cham ((xuc va) OR (luc va)) hanh vi cua tre*.