Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va triet » va thiet, ve triet, cua triet
hanh dai » hanh tai, hanh dao, vanh dai
va trien » va truyen, va thiet, va tuyen
tru nang » tra nang, tri nang, truc nano
va hanh » van hanh, va thanh, va danh
tu nang » tu nong, tu nano, tu lang
tuc va » thuc va, truc va, tuc xa
co tuc » co thuc, co tu, co toc
va co » vo co

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ((tu nang) or (tru nang)) xa hoi. lieu va co tuc va hanh dai ((va triet) or (va trien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((tu nang) OR (tru nang)) xa hoi. lieu va co tuc va hanh dai ((va triet) OR (va trien)).
• Adding a wildcard symbol may retrieve word variants: toc sach ((tu nang) or (tru nang)) xa hoi. lieu va co tuc va hanh dai ((va triet) or (va trien))*.