Perhaps you should try some spelling variations:
sach hoc » cach hoc, sach hoi, mach hoc
cuu dong » cuu cong, cuu tong, cuu long
dong hoc » dong co, dong luc
hoc hang » hoc hanh, hoc bang, hoc tang
hoi benh » hoc benh, hoa benh, hoi binh
nhan tao » nhan tai, nhan dan
tu sach » thu sach, su sach, te sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach hoc tap, nghien cuu dong hoc hang ((khoa hoc) or (hoa hoc)) xa hoi benh nhan tao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoc tap, nghien cuu dong hoc hang ((khoa hoc) OR (hoa hoc)) xa hoi benh nhan tao.
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cuu dong hoc hang ((khoa hoc) or (hoa hoc)) xa hoi benh nhan tao*.