Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
khanh thai » nhanh thai, khanh thanh, khanh thuan
thai cau » thai cao, toan cau, thai van
cau tren » cu tren, dau tren, ca tren
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
xuc van » duc van, luc van, vuc van
ve cac » va cac, vien cac
o hoi » co hoi, o hoc, o hoa
o hai » co hai, so hai, o lai

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc sach ky nang ((o hoi) or (o hai)). hieu ve cac ((xuc van) or (duc tan)) khanh thai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ky nang ((o hoi) OR (o hai)). hieu ve cac ((xuc van) OR (duc tan)) khanh thai cau tren.
• Adding a wildcard symbol may retrieve word variants: thuoc sach ky nang ((o hoi) or (o hai)). hieu ve cac ((xuc van) or (duc tan)) khanh thai cau tren*.