Perhaps you should try some spelling variations:
dau tren » dat tren, dau tieng, dau trong
dau tien » van tien
te sach » toc sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
hieu va » hieu qua
nam tuc » nam thuc, nam truc, nam tu
xa hanh » xa thanh, xa khanh, va hanh
ma hoi » mai hoi, xa hoi, ma hoa

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 ky nang ma hoi. ((hieu va) OR (lieu va)) nam tuc xa hanh vi ((dau tren) or (dau tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang ma hoi. ((hieu va) OR (lieu va)) nam tuc xa hanh vi ((dau tren) OR (dau tien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang ma hoi. ((hieu va) OR (lieu va)) nam tuc xa hanh vi ((dau tren) or (dau tien))".
• Adding a wildcard symbol may retrieve word variants: te sach ky nang ma hoi. ((hieu va) OR (lieu va)) nam tuc xa hanh vi ((dau tren) or (dau tien))*.