Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
trinh le » trinh ly, thinh le, trinh he
va trinh » van trinh, va tinh, lap trinh
cau phuc » cau truc, chau phu, huu phuc
ky tang » ky nang, ky dang, kho tang
tang xa » trang xa, tang ma, lang xa
hieu va » lieu va
phuc va » phuc vu, thuc va, chuc va
le cau » ke cau, le mau, le cap
ke san » ke dan
tu san » thu san, tu ban, tu can

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((ke san) or (tu san)) ky tang xa hoi. ((hieu va) OR (hieu qua)) cau phuc va trinh le cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((ke san) OR (tu san)) ky tang xa hoi. ((hieu va) OR (hieu qua)) cau phuc va trinh le cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((ke san) or (tu san)) ky tang xa hoi. ((hieu va) OR (hieu qua)) cau phuc va trinh le cau tren".
• Adding a wildcard symbol may retrieve word variants: ((ke san) or (tu san)) ky tang xa hoi. ((hieu va) OR (hieu qua)) cau phuc va trinh le cau tren*.