Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
van cam » van nam, van lam, van cau
cam duc » cam xuc, cao duc, pham duc
duc van » duc va, duc tan, duc manh
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
di cua » doi 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.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach v nang ((x hoi) or (x ho)). hieu van cam duc van hanh ((di cua) or (dai cua)) vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach v nang ((x hoi) OR (x ho)). hieu van cam duc van hanh ((di cua) OR (dai cua)) vat.
• Adding a wildcard symbol may retrieve word variants: tu sach v nang ((x hoi) or (x ho)). hieu van cam duc van hanh ((di cua) or (dai cua)) vat*.