Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
thanh di » thanh doi, thanh de, thanh do
vu khach » vu khanh, vu khac, vay khach
va thanh » gia thanh, ban thanh, va tinh
hieu van » hieu va, thien van, lieu va
cao suc » cao su
so sach » so sanh, bo sach, co sach
cao duc » dao duc, giao duc, tao duoc
di cau » da cau, diem cau
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((so sach) or (vu khach)) ky nang x hoi. hieu van ((cao duc) OR (cao suc)) va thanh di cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (vu khach)) ky nang x hoi. hieu van ((cao duc) OR (cao suc)) va thanh di cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sach) or (vu khach)) ky nang x hoi. hieu van ((cao duc) OR (cao suc)) va thanh di cau tren".
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (vu khach)) ky nang x hoi. hieu van ((cao duc) OR (cao suc)) va thanh di cau tren*.