Perhaps you should try some spelling variations:
va trien » va truyen, va tuyen, va tieng
nam thuc » nam thuoc, am thuc, nam thu
bo sach » co sach, hoc sach
thuc va » thuc vat, thuc dan, thuc day
tang ma » mang may, tang van
sang ma » nang ma, sang tao, mang may
hanh va » hang va, hanh vi
hieu ve » hieu va, hieu van
va hanh » van hanh, va thanh, va danh
ve nam » he nam, va nam, le nam
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: bo sach y ((tang ma) or (sang ma)) hoi. hieu ve nam thuc va hanh va ((va trien) or (va thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: bo sach y ((tang ma) OR (sang ma)) hoi. hieu ve nam thuc va hanh va ((va trien) OR (va thiet)).
• Adding a wildcard symbol may retrieve word variants: bo sach y ((tang ma) or (sang ma)) hoi. hieu ve nam thuc va hanh va ((va trien) or (va thiet))*.