Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van phat » va phat, van chat, van phan
hanh tai » thanh tai, hang tai, han tai
so sach » so sanh, bo sach, co sach
sach tu » sach thu, cach tu, sach ty
tu nang » tru nang, tu nong, tu nano
duc van » duc tan, duc manh, duc phan
tai cua » thai cua, tai cuc, tri 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: so sach tu nang ((o hoc) OR (co hoc)). hieu van phat ((duc van) or (duc va)) hanh tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach tu nang ((o hoc) OR (co hoc)). hieu van phat ((duc van) OR (duc va)) hanh tai cua te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach tu nang ((o hoc) OR (co hoc)). hieu van phat ((duc van) or (duc va)) hanh tai cua te*".