Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
te sach » toc sach
sach ky » sac ky, sach y, sach ty
nang xa » lang xa, nang ma, mang xa
hieu ve » hieu va, hieu van
vai cua » dai cua, hai cua, lai cua
ve cam » ve cham, ve cac, va cam
vi cua » di cua
cam o » cham o, cam lo, ca o
o van » vo van, so van, do van

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky ((nang xa) or (nang x)) hoi. hieu ve cam o van hanh ((vi cua) OR (vai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky ((nang xa) OR (nang x)) hoi. hieu ve cam o van hanh ((vi cua) OR (vai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((nang xa) or (nang x)) hoi. hieu ve cam o van hanh ((vi cua) OR (vai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((nang xa) or (nang x)) hoi. hieu ve cam o van hanh ((vi cua) OR (vai cua)) tre*.