Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
ban hanh » ban hang
dau tren » dau tien, dat tren, dau tieng
te sach » toc sach
sach ky » sac ky, sach y, sach ty
nang co » nang cao, nang doc, nang noi
nam xua » nam cua, nam qua, nam luat
nam mua » nam cua, nam qua, nam luat
va danh » va dinh, va dan, va hanh
co hoi » co hoc, co loi
vi dau » vi dai, va dau, bi dau

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 ky nang co hoi. hieu van ((nam xua) OR (nam mua)) ((va danh) or (ban hanh)) vi dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang co hoi. hieu van ((nam xua) OR (nam mua)) ((va danh) OR (ban hanh)) vi dau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang co hoi. hieu van ((nam xua) OR (nam mua)) ((va danh) or (ban hanh)) vi dau tren".
• Adding a wildcard symbol may retrieve word variants: te sach ky nang co hoi. hieu van ((nam xua) OR (nam mua)) ((va danh) or (ban hanh)) vi dau tren*.