Perhaps you should try some spelling variations:
nghien ha » nghiep ha, nghiem hoa, nghiep nha
nhan khoa » nha khoa, khuan khoa, toan khoa
mach hoc » dich hoc, anh hoc, bac hoc
cach hoc » cach thuc, cach thoi, dich hoc
dong hoa » dong hoc, dong co
hoa nhan » hoa phan, hoa han, hoa nhap
khoa hoc » hoa hoc
dan chan » dan gian, dan ca, van chat
ha dong » hoat dong, van dong
chan va » chuan va, nhan va, chat va
va hoc » van hoc

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

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