Perhaps you should try some spelling variations:
tap trung » tap truong, tai trung, tao trung
van hanh » van thanh, ban hanh, van anh
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
va danh » va dinh, va dan, va hanh
vai cua » dai cua, hai cua, lai cua
su sach » so sach, vu sach
ma hoi » mai hoi, xa hoi, ma hoa
va tap » va tac
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
vi cua » di cua

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 v nang ma hoi. hieu va tap trung ((van hanh) OR (va danh)) ((vi cua) OR (vai cua)) viet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach v nang ma hoi. hieu va tap trung ((van hanh) or (va danh)) ((vi cua) OR (vai cua)) viet~".
• Adding a wildcard symbol may retrieve word variants: su sach v nang ma hoi. hieu va tap trung ((van hanh) or (va danh)) ((vi cua) OR (vai cua)) viet*.