Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
benh dot » benh hoc, benh noi, benh dai
san benh » sau benh, tai benh, so benh
hieu van » hieu va, thien van, lieu va
cam duc » cam xuc, pham duc, nam duoc
dot cua » doi cua, do cua, dat cua
cao duc » dao duc, cao suc, giao duc
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
cua tre » cua te, cuu tre, cua triet

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((nang xa) OR (nang ma)) hoi. hieu van ((cam duc) OR (cao duc)) san benh dot cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky ((nang xa) or (nang ma)) hoi. hieu van ((cam duc) OR (cao duc)) san benh dot cua tre~".
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((nang xa) or (nang ma)) hoi. hieu van ((cam duc) OR (cao duc)) san benh dot cua tre*.