Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
so sach » so sanh, bo sach, co sach
ky sang » ky nang, ky dang, duy sang
ky tang » ky nang, ky dang, kho tang
lap hai » lap tai, lap lai, lap hoat
vi cua » vai cua, di cua
dan vi » doan vi, don vi, dan va
va dan » ca dan, va dao, va dau
ve cac » va cac
luc va » duc va, tuc va, loc va
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: so sach ((ky sang) or (ky tang)) lap hai. hieu ((ve cac) or (vien cac)) luc va dan vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((ky sang) OR (ky tang)) lap hai. hieu ((ve cac) OR (vien cac)) luc va dan vi cua te.
• Adding a wildcard symbol may retrieve word variants: so sach ((ky sang) or (ky tang)) lap hai. hieu ((ve cac) or (vien cac)) luc va dan vi cua te*.