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

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 nang)) mai hoi. hieu ((ve cai) or (ve cac)) luc van hanh va la tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((ky sang) OR (ky nang)) mai hoi. hieu ((ve cai) OR (ve cac)) luc van hanh va la tren.
• Adding a wildcard symbol may retrieve word variants: thu sach ((ky sang) or (ky nang)) mai hoi. hieu ((ve cai) or (ve cac)) luc van hanh va la tren*.