Perhaps you should try some spelling variations:
thu mach » thu sach, thuat mach, thu hoach
mach hoc » cach hoc, dich hoc, anh hoc
cuu dong » cuu cong, cuu tong, cuu long
dong hoc » dong co, dong luc
dan khoa » dang khoa, da khoa, san khoa
khoa hoc » hoa hoc
hoa danh » hoa doanh, hoa dan, hop danh
nhan tai » hang tai, van tai, toan tai
nhan va » nhan dan, nhan tao, phan van

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu mach hoc tap, nghien cuu dong hoc dan khoa hoc ma hoa danh ((nhan va) or (nhan tai))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu mach hoc tap, nghien cuu dong hoc dan khoa hoc ma hoa danh ((nhan va) OR (nhan tai)).
• Adding a wildcard symbol may retrieve word variants: thu mach hoc tap, nghien cuu dong hoc dan khoa hoc ma hoa danh ((nhan va) or (nhan tai))*.