Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nha thuoc, cay thuoc
va triet » va trien, ve triet, cua triet
su sach » so sach, vu sach
dan sai » danh sai, doan sai, dan tai
nang ma » tang ma, sang ma, nang cao
hieu le » hieu ve, hieu he, hieu ly
y nang » ky nang, ly nang, v nang
va dan » ca dan, va dao, va dau
ma hoi » mai hoi, xa hoi, ma hoa
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: su sach y nang ma hoi. hieu le ((nam thuoc) OR (nam thu)) va dan sai ((va triet) or (va thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang ma hoi. hieu le ((nam thuoc) OR (nam thu)) va dan sai ((va triet) OR (va thiet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang ma hoi. hieu le ((nam thuoc) OR (nam thu)) va dan sai ((va triet) or (va thiet))".
• Adding a wildcard symbol may retrieve word variants: su sach y nang ma hoi. hieu le ((nam thuoc) OR (nam thu)) va dan sai ((va triet) or (va thiet))*.