Perhaps you should try some spelling variations:
khanh toan » thanh toan, khanh thanh, khanh thuan
thu sach » tu sach, thuat sach, thuoc sach
toan cau » toan cao, toan ban, toan tap
cau tren » cu tren, dau tren, ca tren
xuc van » luc van, vuc van, xuc ban
duc van » duc va, duc tan, duc manh
hieu ve » hieu va, hieu van
y nang » ky nang, ly nang, v nang
ve cac » va cac, vien cac
o lai » o lao
o hoi » co hoi, o hoc, o hai

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 y nang ((o hoi) or (o lai)). hieu ve cac ((xuc van) or (duc van)) khanh toan cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang ((o hoi) OR (o lai)). hieu ve cac ((xuc van) OR (duc van)) khanh toan cau tren.
• Adding a wildcard symbol may retrieve word variants: thu sach y nang ((o hoi) or (o lai)). hieu ve cac ((xuc van) or (duc van)) khanh toan cau tren*.