Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thuat lanh » thuat lap, thuat san
hanh dai » hanh tai, hanh dao, vanh dai
va triet » va thiet, va trien, ve triet
sang ma » tang ma, nang ma, sang tao
phuc va » phuc vu, thuc va, chuc va
va hanh » van hanh, va thanh, va danh
y sang » _ sang, duy sang
va dao » ca dao
dai va » mai va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thuoc sach) or (thuat lanh)) y sang ma hoa. hieu ((va dau) OR (va dao)) phuc va hanh dai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thuoc sach) OR (thuat lanh)) y sang ma hoa. hieu ((va dau) OR (va dao)) phuc va hanh dai va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thuoc sach) or (thuat lanh)) y sang ma hoa. hieu ((va dau) OR (va dao)) phuc va hanh dai va triet".
• Adding a wildcard symbol may retrieve word variants: ((thuoc sach) or (thuat lanh)) y sang ma hoa. hieu ((va dau) OR (va dao)) phuc va hanh dai va triet*.