Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
hang cao » hoang cao, nang cao, hang ca
van cac » van hac, van cau, van bac
cua cau » cua cac, cua chu, cua can
vuc van » duc van, luc van, thuc van
cac vuc » cac nuoc, cac vung, cac cuoc
cao hoc » co hoc, cho hoc, chat hoc
ty hang » ly hang, ty xang, thi hang
cua cay » cua 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: ((te sach) OR (toc sach)) ty hang cao hoc. hieu van cac vuc van hanh vi ((cua cau) OR (cua cay))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ty hang cao hoc. hieu van cac vuc van hanh vi ((cua cau) or (cua cay))~".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ty hang cao hoc. hieu van cac vuc van hanh vi ((cua cau) or (cua cay))*.