Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
dau tren » dau tien, dat tren, dau tieng
hieu va » lieu va, hieu qua
xuc van » duc van, vuc van, xuc ban
luc van » luoc van, luu van, duc van
y lang » o lang, tay lang, yen lang
_ lang » o lang, _ land
va cau » van cau, va cac, va dau
vi dau » vi dai, va dau, bi dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sach ((y lang) or (_ lang)) xa hoi. hieu va cau ((xuc van) OR (luc van)) hanh vi dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sach ((y lang) OR (_ lang)) xa hoi. hieu va cau ((xuc van) OR (luc van)) hanh vi dau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sach ((y lang) or (_ lang)) xa hoi. hieu va cau ((xuc van) OR (luc van)) hanh vi dau tren".
• Adding a wildcard symbol may retrieve word variants: thuat sach ((y lang) or (_ lang)) xa hoi. hieu va cau ((xuc van) OR (luc van)) hanh vi dau tren*.