Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van tham » van thanh, van tuan, van chat
tham duc » pham duc, tham du, than duc
te sach » toc sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
cao hoi » co hoi, cao hoc, tao hoi
va hanh » van hanh, va thanh, ban hanh
va danh » va dinh, va dan, dia danh
chau te » chau tho

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ty nang ((cao hoi) OR (cau hoi)). hieu van tham duc ((va hanh) or (va danh)) lai chau te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty nang ((cao hoi) OR (cau hoi)). hieu van tham duc ((va hanh) OR (va danh)) lai chau te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty nang ((cao hoi) OR (cau hoi)). hieu van tham duc ((va hanh) or (va danh)) lai chau te".
• Adding a wildcard symbol may retrieve word variants: te sach ty nang ((cao hoi) OR (cau hoi)). hieu van tham duc ((va hanh) or (va danh)) lai chau te*.