Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
lam duoc » nam duoc, luat duoc, lam thuoc
lam duc » pham duc, nam duoc, lam dung
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
sang ma » tang ma, nang ma, sang tao
cua tre » cua te, cuu tre, cua triet
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: thu sach ky ((nang xa) or (sang ma)) hoi. hieu van ((lam duc) OR (lam duoc)) van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((nang xa) OR (sang ma)) hoi. hieu van ((lam duc) OR (lam duoc)) van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky ((nang xa) or (sang ma)) hoi. hieu van ((lam duc) OR (lam duoc)) van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((nang xa) or (sang ma)) hoi. hieu van ((lam duc) OR (lam duoc)) van hanh vi cua tre*.