Perhaps you should try some spelling variations:
thay nguoi » tay nguoi, thanh nguoi, thang nguoi
khan thong » khap thong, khau thong, nhan thong
nguoi sinh » nguoi binh, nguoi kinh, nguoi ninh
sach thay » sach tham, sach hay, hoach thay
sinh khoa » sinh hoc, sinh hoat, anh khoa
hoc hang » hoc hanh, hoc bang, hoc tang
hang kho » hang khoa, khang kho, hang cho
kho khan » khoa kham, khoa than
tu sach » thu sach, su sach, te sach
nha hoc » nha thuoc, khoa hoc, nha nuoc
so sach » so sanh, bo sach, co sach
khoa he » hoa he, khoa hoc, khong he

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 nha hoc hang kho khan thong ) or ( so sach thay nguoi sinh khoa he thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach nha hoc hang kho khan thong ) OR ( so sach thay nguoi sinh khoa he thong )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach nha hoc hang kho khan thong ) or ( so sach thay nguoi sinh khoa he thong ))*.