Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
cac truc » cau truc, cac tru, cac trung
dau tren » dau tien, dat tren, dau tieng
tu sach » thu sach, su sach, te sach
truc va » thuc va, thuc vat, trung va
va danh » va dinh, va dan, va hanh
danh vi » hanh vi, dinh vi, danh di
y nang » ky nang, ly nang, may nang
v nang » va nang, vu nang, van nang
co loi » co hoi
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 loi. hieu vien cac truc va danh vi dau tren~.
• Adding a wildcard symbol may retrieve word variants: tu sach ((y nang) or (v nang)) co loi. hieu vien cac truc va danh vi dau tren*.