Perhaps you should try some spelling variations:
sach van » sach han, sach va, bach van
van nang » van quang, van ban, van dong
dua tren » dung tren
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
cau thuc » cau truc, cuu thuc, can thuc
su sach » so sach, vu sach
hanh de » hanh ve, hanh kem
hieu ve » hieu va, hieu van
ve cau » ke cau, va cau, ve cac
mo hoc » mon hoc, co hoc
cua te » cua tu
o hoc » co hoc, so hoc, y hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach van nang ((o hoc) OR (mo hoc)). hieu ve cau thuc van hanh de ((dua tren) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach van nang ((o hoc) OR (mo hoc)). hieu ve cau thuc van hanh de ((dua tren) OR (cua te))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach van nang ((o hoc) OR (mo hoc)). hieu ve cau thuc van hanh de ((dua tren) or (cua te))*".