Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nam thu, nha thuoc
thuoc va » thuc va, thuoc ma, thuong va
sach thu » sach thue, sach thieu, sach tham
hieu van » hieu va, thien van, lieu va
nang xa » lang xa, nang ma, mang xa
va tinh » may tinh
va chua » vua chua, ca chua, va chu
tu sach » thu sach, su sach, te sach
va cua » via cua, ca cua, ma cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach thu ((nang xa) or (nang x)) hoi. hieu van nam thuoc va tinh ((va cua) OR (va chua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thu ((nang xa) OR (nang x)) hoi. hieu van nam thuoc va tinh ((va cua) OR (va chua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thu ((nang xa) or (nang x)) hoi. hieu van nam thuoc va tinh ((va cua) OR (va chua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach thu ((nang xa) or (nang x)) hoi. hieu van nam thuoc va tinh ((va cua) OR (va chua)) tre*.