Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nam vua » nam cua, nam mua, nam qua
va danh » va dinh, va hanh, dia danh
va dan » ca dan, va dao, va dau
vi cau » va cau, ve cau, di cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang x ho. hieu qua ((nam vua) or (nam va)) ((va danh) OR (va dan)) vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x ho. hieu qua ((nam vua) OR (nam va)) ((va danh) OR (va dan)) vi cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x ho. hieu qua ((nam vua) or (nam va)) ((va danh) OR (va dan)) vi cau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x ho. hieu qua ((nam vua) or (nam va)) ((va danh) OR (va dan)) vi cau tren*.