Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
thai son » thai den, thai do, thai hoc
tham soc » cham soc, tham nuoc, ham so
hieu van » hieu va, thien van, lieu va
sang mai » sang ma, sang tai, lang mai
duy sang » duy van, duy can, duy anh
mai hoi » mai khoi, dai hoi, lai hoi
so sach » so sanh, bo sach, co sach
va danh » va dinh, va dan, va hanh
danh vi » hanh vi, dinh vi, danh di
su sach » vu sach
vi su » va su, ve su, ki su

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (so sach)) duy sang mai hoi. hieu van ((tham soc) OR (thai son)) va danh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) duy sang mai hoi. hieu van ((tham soc) OR (thai son)) va danh vi su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (so sach)) duy sang mai hoi. hieu van ((tham soc) OR (thai son)) va danh vi su triet".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (so sach)) duy sang mai hoi. hieu van ((tham soc) OR (thai son)) va danh vi su triet*.