Perhaps you should try some spelling variations:
dang xay » dang van, van xay
va thanh » gia thanh, ban thanh, va tinh
cham luc » cham soc, nhan luc, cham cuu
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
va cham » va chat, va tham
hieu va » lieu va, hieu qua
luc va » duc va, tuc va, loc va
vi cua » vai cua
di cua » dai cua, doi cua, de 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 ((dang xay) or (nang x)) hoi. hieu va cham luc va thanh ((vi cua) OR (di cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((dang xay) OR (nang x)) hoi. hieu va cham luc va thanh ((vi cua) OR (di cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((dang xay) or (nang x)) hoi. hieu va cham luc va thanh ((vi cua) OR (di cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((dang xay) or (nang x)) hoi. hieu va cham luc va thanh ((vi cua) OR (di cua)) tre*.