Perhaps you should try some spelling variations:
su sach » so sach, vu sach
cua tre » cua te, cua triet, dua tren
va hanh » van hanh, va thanh, va danh
hieu va » lieu va, hieu qua
cuu tre » cau tren, cau treo
cao hoi » cau hoi, co hoi, cao hoc
v nang » va nang, vu nang, van nang
y nang » ky nang, ly nang, may nang
bao bo » bac bo, ban bo, nao bo
va bao » va bai
bo va » bao va, do va, so va

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ((y nang) or (v nang)) cao hoi. hieu va bao bo va hanh vi ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((y nang) OR (v nang)) cao hoi. hieu va bao bo va hanh vi ((cua tre) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: su sach ((y nang) or (v nang)) cao hoi. hieu va bao bo va hanh vi ((cua tre) or (cuu tre))*.