Perhaps you should try some spelling variations:
nhoc nhan » ngoc nhan, hoc nhan, nhac nhan
nhan khoa » nha khoa, khuan khoa, toan khoa
nhan taon » nhan trong, nhan thong, nhan tuong
sach hoc » cach hoc, sach hoi, mach hoc
mot nhoc » mot goc, mot nha, bot hoc
khoa hoc » hoa hoc
nhan tao » nhan tai, nhan dan
tu sach » thu sach, su sach, te sach
cuu mot » cua mot, cuu mo, huu mot
ma hoi » mai hoi, xa hoi, ma hoa

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 mot nhoc nhan khoa hoc ma hoi va ((nhan taon) or (nhan tao))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoc tap, nghien cuu mot nhoc nhan khoa hoc ma hoi va ((nhan taon) OR (nhan tao)).
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cuu mot nhoc nhan khoa hoc ma hoi va ((nhan taon) or (nhan tao))*.