Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
hieu van » hieu va, thien van, hieu ve
van hanh » van thanh, ban hanh, van anh
hanh hai » thanh hai, nhanh hai, hang hai
dau tren » dau tien, dat tren, dau tieng
tu sach » su sach, te sach, tu cach
ly nang » ky nang, ly hang, ly vang
nam luc » nang luc, nhan luc, nam thuc
luc van » luoc van, luu van, duc van
hai dau » han dau, hai dan, hai hau

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) OR (tu sach)) ly nang x ho. ((hieu van) or (lieu va)) nam luc van hanh hai dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (tu sach)) ly nang x ho. ((hieu van) OR (lieu va)) nam luc van hanh hai dau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) OR (tu sach)) ly nang x ho. ((hieu van) or (lieu va)) nam luc van hanh hai dau tren".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) OR (tu sach)) ly nang x ho. ((hieu van) or (lieu va)) nam luc van hanh hai dau tren*.