Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
cua viet » ca viet, hoa viet, cua vat
hanh vai » hanh vi, hanh va, hanh tai
cac cuoc » cac nuoc, ca cuoc, cac quoc
vien cac » vien bach, vien dai, vien da
dai hoi » dai hoc, dai hai, dai moi
sach ty » sach y, sach tu, sach thu
mai hoi » mai khoi, lai hoi, mai doi
cuoc va » nuoc va, duoc va, quoc va
va hanh » van hanh, va thanh, va danh
ty nang » ky nang, ty xang, ty hang
vai cua » dai cua, hai cua, lai cua
su sach » so sach, vu sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty nang ((mai hoi) or (dai hoi)). hieu vien cac cuoc va hanh vai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty nang ((mai hoi) OR (dai hoi)). hieu vien cac cuoc va hanh vai cua viet.
• Adding a wildcard symbol may retrieve word variants: su sach ty nang ((mai hoi) or (dai hoi)). hieu vien cac cuoc va hanh vai cua viet*.