Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nam thu, nha thuoc
thuat san » thuat toan, thuat song, thuat lanh
hieu van » hieu va, thien van, lieu va
thuoc ma » hoc ma, duoc ma
cua tre » cua te, cua triet, dua tren
ma hanh » va hanh, da hanh, na hanh
tu sach » thu sach, su sach, te sach
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
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 (thuat san)) ky tang xa hoi. hieu van nam thuoc ma hanh vi ((cua tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thuat san)) ky tang xa hoi. hieu van nam thuoc ma hanh vi ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thuat san)) ky tang xa hoi. hieu van nam thuoc ma hanh vi ((cua tre) OR (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thuat san)) ky tang xa hoi. hieu van nam thuoc ma hanh vi ((cua tre) OR (cuu tre))*.