Perhaps you should try some spelling variations:
nghien cac » nghiep cach, nghien cuu, nghiep cay
hang khoa » dung khoa
cac dong » cac duong, cac cong, cac dang
dong hoa » dong hoc, dong co
hoa hang » hoat hang, hoa lang, hoa han
khoa hoc » hoa hoc
nhan dan » phan dau, gian dan, nhan tai
vu sach » vu bach, vu khach
su sach » so sach
dao tap » dao tao, dao tay, dao gap
hoc xa » hoc ma
hoi ca » hoi cua, hoi cac, hoi cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((vu sach) OR (su sach)) dao tap, nghien cac dong hoa hang khoa hoc xa hoi ca nhan dan~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((vu sach) OR (su sach)) dao tap, nghien cac dong hoa hang khoa hoc xa hoi ca nhan dan".
• Adding a wildcard symbol may retrieve word variants: ((vu sach) OR (su sach)) dao tap, nghien cac dong hoa hang khoa hoc xa hoi ca nhan dan*.