Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va triet » va thiet, va trien, ve triet
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
cam tuc » cam xuc, cam tu, nam thuc
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
tuc va » thuc va, truc va, tuc xa
va cam » va cham, va cac, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky ((nang xa) or (nang ma)) hoi. hieu va cam tuc va hanh vi ((cua tre) or (va triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((nang xa) OR (nang ma)) hoi. hieu va cam tuc va hanh vi ((cua tre) OR (va triet)).
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((nang xa) or (nang ma)) hoi. hieu va cam tuc va hanh vi ((cua tre) or (va triet))*.