Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
van quang » van quan, tran quang, van tuan
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
vien cac » vien bach, vien dai, vien da
cac thuc » cach thuc, cac thu, can thuc
van nang » van ban, van dong, van dung
su sach » so sach, vu sach
de cau » ke cau, le cau, da cau
ve cau » ke cau, va cau, ve cac

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: su sach ((van nang) OR (van quang)) x ho. hieu vien cac thuc van hanh ((de cau) OR (ve cau)) tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((van nang) or (van quang)) x ho. hieu vien cac thuc van hanh ((de cau) OR (ve cau)) tren~".
• Adding a wildcard symbol may retrieve word variants: su sach ((van nang) or (van quang)) x ho. hieu vien cac thuc van hanh ((de cau) OR (ve cau)) tren*.