Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
sach duoc » sach nuoc, sach dao, sach dung
sach luoc » sach nuoc, sach luan, bach tuoc
van hanh » van thanh, ban hanh, van anh
lang mai » lang dai, lang hai, lang man
ky lang » ky nang, ky dang, ky tang
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 lang mai hoi. hieu vien ((sach luoc) OR (sach duoc)) van hanh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu bai) OR (tu bat)) ky lang mai hoi. hieu vien ((sach luoc) OR (sach duoc)) van hanh vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu bai) or (tu bat)) ky lang mai hoi. hieu vien ((sach luoc) OR (sach duoc)) van hanh vi cua te".
• Adding a wildcard symbol may retrieve word variants: ((tu bai) or (tu bat)) ky lang mai hoi. hieu vien ((sach luoc) OR (sach duoc)) van hanh vi cua te*.