Perhaps you should try some spelling variations:
doanh khoa » toan khoa
sach moi » sach doi, sach hoi, bach mai
khoa hoc » hoa hoc
phat van » pham van, phan van, phap van
so sach » so sanh, bo sach, co sach
moi dap » hoi dap, doi dap, moi dan
mot van » moi van, mot lan, hoat van
hoa va » hoa van, hoa xa, hoa vo

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach moi dap, nghien cuu ((mot van) OR (mot vai)) doanh khoa hoc ma hoa va phat van~".
• Adding a wildcard symbol may retrieve word variants: so sach moi dap, nghien cuu ((mot van) OR (mot vai)) doanh khoa hoc ma hoa va phat van*.