Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
van cac » van hac, van cau, van bac
cac luc » cau luc, coc luc, cac nuoc
luc gia » luoc gia, duc gia, quoc gia
doi cua » dai cua, hoi cua
di cua » dai cua, de cua, do cua
x hoi » xa hoi, o hoi, 5 hoi

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: tu sach ty nang ((x hoi) OR (x ho)). hieu van cac luc gia thanh ((di cua) OR (doi cua)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang ((x hoi) or (x ho)). hieu van cac luc gia thanh ((di cua) OR (doi cua)) tre~".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang ((x hoi) or (x ho)). hieu van cac luc gia thanh ((di cua) OR (doi cua)) tre*.