Perhaps you should try some spelling variations:
thanh thai » thanh hai, nhanh thai, thanh thao
thanh tai » thanh hai, thanh toan, doanh tai
cau tren » cu tren, dau tren, ca tren
hieu van » hieu va, thien van, lieu va
xuc van » duc van, luc van, vuc van
tu sach » thu sach, su sach, te sach
hac xuc » chat xuc
sach ky » sac ky, sach y, sach ty
van hac » van hoc, van ha, van hai
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.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang ((o hoi) or (o hai)). hieu van hac xuc van ((thanh thai) OR (thanh tai)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((o hoi) OR (o hai)). hieu van hac xuc van ((thanh thai) OR (thanh tai)) cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((o hoi) or (o hai)). hieu van hac xuc van ((thanh thai) OR (thanh tai)) cau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) or (o hai)). hieu van hac xuc van ((thanh thai) OR (thanh tai)) cau tren*.