Perhaps you should try some spelling variations:
nghien cac » nghiep cach, nghien cuu, nghiep cay
hang khoa » dung khoa
vu khach » vu khanh, vu khac, vay khach
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
su sach » so sach, vu 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 khach) or (su sach)) dao tap, nghien cac dong hoa hang khoa hoc xa hoi ca nhan dan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((vu khach) 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 khach) or (su sach)) dao tap, nghien cac dong hoa hang khoa hoc xa hoi ca nhan dan*.