Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
dang xay » dang van, van xay
hieu van » hieu va, thien van, lieu va
dang xa » lang xa, dang ha, dang va
sach ky » sac ky, sach y, sach ty
nam luc » nang luc, nhan luc, nam thuc
va hanh » van hanh, va thanh, va danh
vai cua » dai cua, hai cua, lai cua
luc va » duc va, tuc va, loc va
vi 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: thu sach ky ((dang xa) or (dang xay)) hoi. hieu van nam luc va hanh ((vi cua) OR (vai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((dang xa) OR (dang xay)) hoi. hieu van nam luc va hanh ((vi cua) OR (vai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky ((dang xa) or (dang xay)) hoi. hieu van nam luc va hanh ((vi cua) OR (vai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((dang xa) or (dang xay)) hoi. hieu van nam luc va hanh ((vi cua) OR (vai cua)) tre*.