Perhaps you should try some spelling variations:
nhanh thanh » phan thanh, nhanh tinh
thanh mau » hanh mau, thanh san, thanh hai
mau tren » dau tren, cau tren, mau tieng
duc van » duc va, duc tan, duc manh
vuc van » luc van, thuc van, chuc van
tu sach » thu sach, su sach, te sach
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 hoc » co hoc, mo hoc, so hoc

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