Perhaps you should try some spelling variations:
trinh cao » trinh chao, trinh co, trinh cau
soi viet » so viet, hoi viet, oi viet
doi viet » dai viet, hoi viet, oi viet
cac cong » cua cong
dac cho » day cho, danh cho
cac dac » cac dan, cac dai, cac bac
cho doi » cho moi, cuoc doi, cho tuoi
cac cay » ca cay, cac cam, cac cap
cao lan » cao van, cao dang, cao tang
lanh va » hanh va, anh va, doanh va
co soi » cot soi, co so, co hoi
cay co » tay co, cay cong
lan va » luan va, lan van, lang va

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( cong trinh cao ((lanh va) or (lanh dao)) cac cay co soi viet nam ) or ((( cong trinh cao lan va cac ((cac co) OR (cac cong)) doi viet nam ) or ( cong trinh cao lan va cac dac cho doi viet nam ))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( cong trinh cao ((lanh va) OR (lanh dao)) cac cay co soi viet nam ) OR ((( cong trinh cao lan va cac ((cac co) OR (cac cong)) doi viet nam ) OR ( cong trinh cao lan va cac dac cho doi viet nam )))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( cong trinh cao ((lanh va) or (lanh dao)) cac cay co soi viet nam ) or ((( cong trinh cao lan va cac ((cac co) OR (cac cong)) doi viet nam ) or ( cong trinh cao lan va cac dac cho doi viet nam ))))".
• Adding a wildcard symbol may retrieve word variants: (( cong trinh cao ((lanh va) or (lanh dao)) cac cay co soi viet nam ) or ((( cong trinh cao lan va cac ((cac co) OR (cac cong)) doi viet nam ) or ( cong trinh cao lan va cac dac cho doi viet nam ))))*.