Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hanh vai » hanh vi, hanh va, hanh tai
van hanh » van thanh, ban hanh, van anh
dua tren » dung tren
mai hoi » mai khoi, dai hoi, lai hoi
ky dang » ky nang, ky danh
luc van » luoc van, luu van, duc van
ky sang » ky nang, ky tang, duy sang
vai dua » dai dua, vai cua
ve cac » va cac, vien cac
ve cai » va cai, ve tai, ve cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ((ky sang) or (ky dang)) mai hoi. hieu ((ve cai) or (ve cac)) luc van hanh vai dua tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((ky sang) OR (ky dang)) mai hoi. hieu ((ve cai) OR (ve cac)) luc van hanh vai dua tren.
• Adding a wildcard symbol may retrieve word variants: thu sach ((ky sang) or (ky dang)) mai hoi. hieu ((ve cai) or (ve cac)) luc van hanh vai dua tren*.