Perhaps you should try some spelling variations:
sach thi » sach thu, sach tai, sach thieu
thi hanh » thi thanh
thanh de » hanh de, thanh ve, thanh do
va thanh » gia thanh, ban thanh, va tinh
hieu van » hieu va, thien van, lieu va
te sach » toc sach
cac luc » cau luc, cac nuoc, cac cuoc
de cua » le cua, te cua, dieu cua
cua te » cua tu
o hoc » mo 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: te sach thi hanh ((o hoc) or (co hoc)). hieu van ((cac luc) or (coc luc)) va thanh de cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach thi hanh ((o hoc) OR (co hoc)). hieu van ((cac luc) OR (coc luc)) va thanh de cua te.
• Adding a wildcard symbol may retrieve word variants: te sach thi hanh ((o hoc) or (co hoc)). hieu van ((cac luc) or (coc luc)) va thanh de cua te*.