Perhaps you should try some spelling variations:
ban benh » san benh, ba benh, ban banh
quoc ban » quoc bao, quoc lan, quoc quan
tu sach » thu sach, su sach, te sach
van lam » van nam
benh vi » benh va, benh ve, benh li
van cam » van nam, van cau, van dam
sach ky » sac ky, sach y, sach ty
nang xa » lang xa, nang ma, mang xa
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: tu sach ky ((nang xa) or (nang x)) hoi. hieu ((van cam) or (van lam)) quoc ban benh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang x)) hoi. hieu ((van cam) OR (van lam)) quoc ban benh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (nang x)) hoi. hieu ((van cam) or (van lam)) quoc ban benh vi cua tre*.