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