Perhaps you should try some spelling variations:
danh tac » danh bac, doanh tai, danh thuc
tac vang » cac van, tac dung, tac dong
vang hoc » nang hoc, vung hoc, bang hoc
hoc viet » hoc hien
canh tac » canh tay, canh giac, cong tac
tac can » tac quan, tac danh
can hoc » dan hoc, cao hoc, can ho
tac van » cac van, tac va, tac quan
van hoc » van hoa

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

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