Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
va hanh » van hanh, va thanh, va danh
cua tre » cuu tre, cua triet, dua tren
y nang » ky nang, ly nang, v nang
cua tu » cua tuc, cua su, cua cu

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 y nang xa hoi. hieu va cac duc va hanh vi ((((cua tre) or (cua te))) or (cua tu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang xa hoi. hieu va cac duc va hanh vi ((((cua tre) OR (cua te))) OR (cua tu)).
• Adding a wildcard symbol may retrieve word variants: toc sach y nang xa hoi. hieu va cac duc va hanh vi ((((cua tre) or (cua te))) or (cua tu))*.