Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » thien van, lieu va, hieu ve
van hanh » van thanh, ban hanh, van anh
hanh vai » hanh vi, hanh va, hanh tai
sach ty » sach y, sach tu, sach thu
ty tang » tay tang, ty xang, ty hang
tang co » tang cho, nang co, tang o
hieu va » lieu va, hieu qua
cac vuc » cac nuoc, cac vung, cac cuoc
vuc van » duc van, luc van, thuc van
cua cau » cua cac, cua chu, cua can
cua cay » cua cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ty tang co hoc. ((hieu van) or (hieu va)) cac vuc van hanh vai ((cua cau) or (cua cay))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty tang co hoc. ((hieu van) OR (hieu va)) cac vuc van hanh vai ((cua cau) OR (cua cay))*.