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

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

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