Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
ban tinh » ban thanh, quan tinh, ban hanh
cac cua » cach cua, cac qua, ca cua
su sach » so sach, vu sach
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
hieu va » lieu va, hieu qua
vi cau » va cau, di cau, viet cau
ve cau » ke cau, va cau, ve cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (toc sach)) ky lang xa hoi. hieu va cac cua ban tinh ((vi cau) OR (ve cau)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (toc sach)) ky lang xa hoi. hieu va cac cua ban tinh ((vi cau) OR (ve cau)) tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (toc sach)) ky lang xa hoi. hieu va cac cua ban tinh ((vi cau) OR (ve cau)) tren".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (toc sach)) ky lang xa hoi. hieu va cac cua ban tinh ((vi cau) OR (ve cau)) tren*.