Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
te sach » toc sach
va hanh » van hanh, va thanh, va danh
hieu va » lieu va, hieu qua
ty nang » ky nang, ty xang, ly nang
ty hang » ly hang, ty xang, thi hang
cu tren » tu tren, dua tren
va dam » van dam, va dao, va dau
dam tu » nam tu, cam tu, tam tu
x hoi » xa hoi, o hoi, x ho

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