Perhaps you should try some spelling variations:
canh tac » canh tay, canh giac, cong tac
hoc viet » hoc hien
danh tuc » danh thuc, danh tu, danh muc
tac han » tac nhan, tac ha, tac can
tac van » tac vang, cac van, tac va
ha hoc » hoa hoc, nha hoc, va hoc
xa hoc » xa hoi, va hoc, xa hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((( ((canh tac) or (doanh tai)) ha hoc viet nam ) or ( danh ((tac han) or (tac van)) hoc viet nam ))) or ( danh tuc xa hoc viet nam ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((( ((canh tac) OR (doanh tai)) ha hoc viet nam ) OR ( danh ((tac han) OR (tac van)) hoc viet nam ))) OR ( danh tuc xa hoc viet nam )).
• Adding a wildcard symbol may retrieve word variants: (((( ((canh tac) or (doanh tai)) ha hoc viet nam ) or ( danh ((tac han) or (tac van)) hoc viet nam ))) or ( danh tuc xa hoc viet nam ))*.