Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
nam thuoc » nam thuc, nam thu, nha thuoc
thuoc ma » hoc ma, duoc ma
hieu van » hieu va, thien van, lieu va
ly quang » le quang, vu quang
ly vang » ly hang, ly van
ma hanh » va hanh, da hanh, na hanh
va cuu » va cau, va chu
va huu » vu huu
x hoi » xa hoi, o hoi, x ho

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 ((ly vang) OR (ly quang)) x hoi. hieu van nam thuoc ma hanh ((va cuu) or (va huu)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ((ly vang) OR (ly quang)) x hoi. hieu van nam thuoc ma hanh ((va cuu) OR (va huu)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach ((ly vang) OR (ly quang)) x hoi. hieu van nam thuoc ma hanh ((va cuu) or (va huu)) tre".
• Adding a wildcard symbol may retrieve word variants: thuoc sach ((ly vang) OR (ly quang)) x hoi. hieu van nam thuoc ma hanh ((va cuu) or (va huu)) tre*.