Perhaps you should try some spelling variations:
va triet » va trien, ve triet, cua triet
nam thuc » nam thuoc, am thuc, nam thu
te sach » toc sach
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
sach ky » sac ky, sach y, sach ty
hieu le » hieu ve, hieu he, hieu ly
hoa hoi » khoa hoi, hoa hoc, hoa doi
ky dang » ky nang, ky danh
le nam » ly nam, he nam, le na
ha hoi » ha noi, xa hoi, va hoi
thiet » thieu

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 ky dang ((ha hoi) or (hoa hoi)). hieu le nam thuc va hanh vi ((va triet) OR (va thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky dang ((ha hoi) OR (hoa hoi)). hieu le nam thuc va hanh vi ((va triet) OR (va thiet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky dang ((ha hoi) or (hoa hoi)). hieu le nam thuc va hanh vi ((va triet) OR (va thiet))".
• Adding a wildcard symbol may retrieve word variants: te sach ky dang ((ha hoi) or (hoa hoi)). hieu le nam thuc va hanh vi ((va triet) OR (va thiet))*.