Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
truc van » truc va, thuc van, truc ban
so sach » so sanh, bo sach, co sach
ty nang » ky nang, ty xang, ly nang
ty hang » ly hang, ty xang, thi hang
va cau » van cau, va cac, va dau
di cua » dai cua, doi cua, do cua
de cua » le cua, te cua, dieu cua
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ((ty nang) or (ty hang)) x hoi. lieu va cau truc van hanh ((di cua) OR (de cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((ty nang) OR (ty hang)) x hoi. lieu va cau truc van hanh ((di cua) OR (de cua)) tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((ty nang) or (ty hang)) x hoi. lieu va cau truc van hanh ((di cua) OR (de cua)) tre*".