Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
va danh » va dinh, va hanh, dia danh
hieu ve » hieu va, hieu van
tu sach » thu sach, su sach, te sach
cac tuc » cac toc, cac tu, cac tac
v nang » va nang, vu nang, van nang
ve cac » va cac, vien cac
y nang » ky nang, ly nang, may nang
va dan » ca dan, va dao, va dau
vi dau » vi dai, va dau, bi dau

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y nang) OR (v nang)) co hoc. hieu ve cac tuc ((va danh) OR (va dan)) vi dau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y nang) or (v nang)) co hoc. hieu ve cac tuc ((va danh) OR (va dan)) vi dau tren~".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y nang) or (v nang)) co hoc. hieu ve cac tuc ((va danh) OR (va dan)) vi dau tren*.