Perhaps you should try some spelling variations:
khanh nhanh » khanh thanh, thanh nhan, nhanh thanh
nhanh cau » nhanh cay, thanh chau, nhanh ha
thu sach » tu sach, thuat sach, thuoc sach
cau tren » cu tren, dau tren, ca tren
sach ky » sac ky, sach y, sach ty
xuc van » luc van, vuc van, xuc ban
duc van » duc va, duc tan, duc manh
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
o hai » co hai, so hai, o lai
o hoa » do hoa, so hoa, o ha

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