Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
hieu van » hieu va, thien van, lieu va
cau thuc » cau truc, cuu thuc, can thuc
hoc sach » hoc sinh, hoc cac, hoc anh
van cau » van dau, van hau, van chat
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
danh vu » danh tu, anh vu, danh du
so sach » so sanh, bo sach, co sach
y song » _ song, c song, hay song
k song » _ song, c song
vu va » vu van, tu va, su va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((so sach) or (hoc sach)) ((y song) OR (k song)) xa hoi. hieu van cau thuc va danh vu va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (hoc sach)) ((y song) OR (k song)) xa hoi. hieu van cau thuc va danh vu va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sach) or (hoc sach)) ((y song) OR (k song)) xa hoi. hieu van cau thuc va danh vu va triet".
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (hoc sach)) ((y song) OR (k song)) xa hoi. hieu van cau thuc va danh vu va triet*.