Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
nang mai » nang ma, nang tai, lang mai
mai khoa » tai khoa, may khoa, dai khoa
sach ky » sac ky, sach y, sach ty
vai cau » va cau, van cau, vai cac
cam luc » cam xuc, cau luc
su sach » so sach, vu sach
hieu ve » hieu van
hieu va » lieu va, hieu qua
va dan » va dao, va dau, va dap
ca dan » cac dan, ca dao

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang mai khoa. ((hieu ve) OR (hieu va)) cam luc ((va dan) OR (ca dan)) vai cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang mai khoa. ((hieu ve) or (hieu va)) cam luc ((va dan) OR (ca dan)) vai cau tren~".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang mai khoa. ((hieu ve) or (hieu va)) cam luc ((va dan) OR (ca dan)) vai cau tren*.