Perhaps you should try some spelling variations:
nhanh thanh » phan thanh, nhanh tinh
thanh dau » thanh dat, thanh dam, thanh mau
van nhanh » van thanh, van hanh, van khanh
dau tren » dau tien, dat tren, dau tieng
vuc van » duc van, luc van, thuc van
cac vuc » cac nuoc, cac vung, cac cuoc
hieu ve » hieu va, hieu van
sach ky » sac ky, sach ty, sach kem
ve cac » va cac, vien cac
o hoc » co hoc, mo hoc, so hoc
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: tu ((sach ky) or (sach y)) nang ((o hoc) or (o hai)). hieu ve cac vuc van nhanh thanh dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach y)) nang ((o hoc) OR (o hai)). hieu ve cac vuc van nhanh thanh dau tren.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sach y)) nang ((o hoc) or (o hai)). hieu ve cac vuc van nhanh thanh dau tren*.