Perhaps you should try some spelling variations:
sach ky » sac ky, sach y, sach ty
doi cua » dai cua, hoi cua, dong cua
va hanh » van hanh, va thanh, va danh
cau duc » cao duc, cau luc, chu duc
hieu va » lieu va, hieu qua
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
mang xa » lang xa, mang may, dang xay
va cau » van cau, va cac, va dau
vi cua » vai cua, di cua

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 ((mang xa) or (nang ma)) hoi. hieu va cau duc va hanh ((vi cua) or (doi cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((mang xa) OR (nang ma)) hoi. hieu va cau duc va hanh ((vi cua) OR (doi cua)) tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((mang xa) or (nang ma)) hoi. hieu va cau duc va hanh ((vi cua) or (doi cua)) tre*.