Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
ban danh » ban doanh, ban hanh, ban dan
thuc ban » thuoc ban, thuc dan, thu ban
hieu van » hieu va, thien van, lieu va
cua tre » cua te, cua triet, dua tren
danh vi » hanh vi, dinh vi, danh di
tu sach » thu sach, su sach, te sach
lang xa » lang ha, dang xay, lang van
ty lang » tay lang, ty xang, ty hang
vu sach » vu bach, su sach, vu khach
cuu tre » cau tren, cau treo

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) or (vu sach)) ty lang xa hoi. hieu van nam thuc ban danh vi ((cua tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (vu sach)) ty lang xa hoi. hieu van nam thuc ban danh vi ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (vu sach)) ty lang xa hoi. hieu van nam thuc ban danh vi ((cua tre) OR (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (vu sach)) ty lang xa hoi. hieu van nam thuc ban danh vi ((cua tre) OR (cuu tre))*.