Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
te sach » toc sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
van cac » van hac, van cau, dan cac
van bac » van ban, van bao, van hac
vai cua » dai cua, hai cua, lai cua
nang o » nang co, nang ho, nang ro
vi cua » di cua
o hai » co hai, so hai, o lai

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 ty nang o hai. hieu ((van cac) OR (van bac)) vo van hanh ((vi cua) or (vai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty nang o hai. hieu ((van cac) OR (van bac)) vo van hanh ((vi cua) OR (vai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty nang o hai. hieu ((van cac) OR (van bac)) vo van hanh ((vi cua) or (vai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: te sach ty nang o hai. hieu ((van cac) OR (van bac)) vo van hanh ((vi cua) or (vai cua)) tre*.