Perhaps you should try some spelling variations:
sach nuoc » sach duoc, cac nuoc, bach tuoc
hanh lai » hanh lam, hanh tai, thanh lap
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cua triet, dua tren
va hanh » van hanh, va thanh, va danh
tu sach » thu sach, su sach, te sach
hieu va » lieu va
nang ho » nang hoc, nang co, tang ho
ty nang » ky nang, ty xang, ty hang
cuu tre » cau tren, cau treo
ho hoi » hoc hoi, hoa hoi, hoi hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ty nang ho hoi. ((hieu va) OR (hieu qua)) sach nuoc va hanh lai ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang ho hoi. ((hieu va) OR (hieu qua)) sach nuoc va hanh lai ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang ho hoi. ((hieu va) OR (hieu qua)) sach nuoc va hanh lai ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang ho hoi. ((hieu va) OR (hieu qua)) sach nuoc va hanh lai ((cua tre) or (cuu tre))*.