Perhaps you should try some spelling variations:
nhanh thai » nhanh thi, nhanh thanh, nhanh thang
van nhanh » van thanh, van hanh, van khanh
cau tren » dau tren, ca tren, cau treo
tu sach » thu sach, su sach, te sach
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
cu tren » tu tren, dua tren
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
o hai » co hai, so hai, o lai
o hoi » co hoi, o hoc, o hoa

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((o hoi) OR (o hai)). hieu ve cac duc van nhanh thai ((cau tren) OR (cu tren))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((o hoi) or (o hai)). hieu ve cac duc van nhanh thai ((cau tren) OR (cu tren))~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) or (o hai)). hieu ve cac duc van nhanh thai ((cau tren) OR (cu tren))*.