Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien sach » vien bach, dien sach, viet sach
luoc van » luoc can, luc van, luot van
nang mai » nang ma, nang tai, lang mai
luoc va » nuoc va, duoc va, loc va
mai hoi » mai khoi, dai hoi, lai hoi
vi cua » vai cua, di cua
tu bai » tu ban, te bai
tu bat » tu ban, tu dat
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 bat)) ky nang mai hoi. hieu vien sach ((luoc van) OR (luoc va)) hanh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu bai) OR (tu bat)) ky nang mai hoi. hieu vien sach ((luoc van) OR (luoc va)) hanh vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu bai) or (tu bat)) ky nang mai hoi. hieu vien sach ((luoc van) OR (luoc va)) hanh vi cua te".
• Adding a wildcard symbol may retrieve word variants: ((tu bai) or (tu bat)) ky nang mai hoi. hieu vien sach ((luoc van) OR (luoc va)) hanh vi cua te*.