Perhaps you should try some spelling variations:
duong sach » duong manh
va triet » va thiet, va trien, ve triet
hieu van » hieu va, thien van, lieu va
danh di » danh du, xanh di, danh dien
va danh » va dinh, va dan, va hanh
dao tuc » dao duc
dau tuc » dau tu, cau truc, dau nuoc
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
y nang » ky nang, ly nang, v nang
di va » dai va, di vao, doi va

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 (duong sach)) y nang ma hoi. hieu van ((dau tuc) or (dao tuc)) va danh di va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (duong sach)) y nang ma hoi. hieu van ((dau tuc) OR (dao tuc)) va danh di va triet.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (duong sach)) y nang ma hoi. hieu van ((dau tuc) or (dao tuc)) va danh di va triet*.