Perhaps you should try some spelling variations:
thue nang » thien nang, thuat nang, thi nang
cua triet » cua viet, va triet
van khanh » van thanh, van hanh, van anh
sach thue » sach thu, sach thieu, sach tham
su triet » su viet, su tien, ve triet
cam thuc » am thuc, nam thuc, cam thu
khanh vi » hanh vi, khanh v, nhanh vi
thuc van » thuc vat, thuc dan, thuc va
so sach » so sanh, bo sach, co sach
hieu ve » hieu va, hieu van
ve cam » ve cham, ve cac, va cam
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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 thue nang ((x hoi) OR (o hoi)). hieu ve cam thuc van khanh vi ((cua triet) or (su triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach thue nang ((x hoi) OR (o hoi)). hieu ve cam thuc van khanh vi ((cua triet) OR (su triet))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach thue nang ((x hoi) OR (o hoi)). hieu ve cam thuc van khanh vi ((cua triet) or (su triet))*".