Perhaps you should try some spelling variations:
toan hanh » toan thanh, toan anh, tran hanh
duc toan » duc tan, duc ton, duc hoan
cao duc » dao duc, cao suc, giao duc
hieu ve » hieu va, hieu van
sach v » sach va, sach 2, sach vay
nang o » nang co, nang ho, nang ro
ve cao » va cao, ve bao, ve cac
o hoi » co hoi, o hoc, o hai
ki su » ky su
ve su » va su

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach v) OR (sach y)) nang o hoi. hieu ve cao duc toan hanh ((ki su) or (ve su)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach v) OR (sach y)) nang o hoi. hieu ve cao duc toan hanh ((ki su) OR (ve su)) triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach v) OR (sach y)) nang o hoi. hieu ve cao duc toan hanh ((ki su) or (ve su)) triet*".