Perhaps you should try some spelling variations:
hieu viet » sieu viet, hieu viec, lieu viet
viet sach » viet anh, dien sach, viet tech
nang mai » nang ma, nang tai, lang mai
mai khoi » mai khoa, tai khoa, cac khoi
luoc van » luoc can, luoc va, luot van
luc van » luu van, duc van, luc va
vi cua » vai cua, di cua
tu bai » tu bat, te bai
tu ban » thu ban, te ban
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu bai) or (tu ban)) ky nang mai khoi. hieu viet sach ((luoc van) OR (luc van)) hanh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu bai) OR (tu ban)) ky nang mai khoi. hieu viet sach ((luoc van) OR (luc van)) hanh vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu bai) or (tu ban)) ky nang mai khoi. hieu viet sach ((luoc van) OR (luc van)) hanh vi cua te".
• Adding a wildcard symbol may retrieve word variants: ((tu bai) or (tu ban)) ky nang mai khoi. hieu viet sach ((luoc van) OR (luc van)) hanh vi cua te*.