Perhaps you should try some spelling variations:
sach nuoc » sach duoc, bach tuoc, dich nuoc
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
hanh lai » hanh lam, hanh tai, thanh lap
te sach » toc sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
hieu va » lieu va, hieu qua
va hanh » van hanh, va thanh, va danh
lai cua » dai cua, hai cua, lai chau
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ty nang o hoi. hieu va ((sach nuoc) or (cac nuoc)) va hanh lai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty nang o hoi. hieu va ((sach nuoc) OR (cac nuoc)) va hanh lai cua tre.
• Adding a wildcard symbol may retrieve word variants: te sach ty nang o hoi. hieu va ((sach nuoc) or (cac nuoc)) va hanh lai cua tre*.