Perhaps you should try some spelling variations:
va hanh » van hanh, va thanh, va danh
cau loc » hau loc, cau hoc, cau luc
sach ky » sach y, sach ty, sach kem
lang xa » lang ha, dang xay, lang van
qua cau » quan cau, qua cac, qua ca
sac ky » cac ky, sai ky
loc va » hoc va, luc va
vai va » mai va, dai va, hai va
vi va » vi van, vu va, bi va

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: so ((sach ky) OR (sac ky)) lang xa hoi. hieu qua cau loc va hanh ((vi va) OR (vai va)) trien~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((sach ky) or (sac ky)) lang xa hoi. hieu qua cau loc va hanh ((vi va) OR (vai va)) trien~".
• Adding a wildcard symbol may retrieve word variants: so ((sach ky) or (sac ky)) lang xa hoi. hieu qua cau loc va hanh ((vi va) OR (vai va)) trien*.