Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
nang mai » nang ma, nang tai, lang mai
cap nuoc » dat nuoc
hieu va » lieu va, hieu qua
va danh » va dinh, va hanh, dia danh
sach ky » sac ky, sach y, sach ty
ca tren » cau tren, cu tren, la tren
hieu ve » hieu van
mai hoi » mai khoi, dai hoi, lai hoi
va dan » ca dan, va dao, va dau
vi ca » vit ca, li ca, va ca

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc sach ky nang mai hoi. ((hieu ve) or (hieu va)) cap nuoc ((va danh) OR (va dan)) vi ca tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ky nang mai hoi. ((hieu ve) OR (hieu va)) cap nuoc ((va danh) OR (va dan)) vi ca tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach ky nang mai hoi. ((hieu ve) or (hieu va)) cap nuoc ((va danh) OR (va dan)) vi ca tren".
• Adding a wildcard symbol may retrieve word variants: thuoc sach ky nang mai hoi. ((hieu ve) or (hieu va)) cap nuoc ((va danh) OR (va dan)) vi ca tren*.