Perhaps you should try some spelling variations:
thanh van » thanh san, thanh toan, thanh phan
toc sach » hoc sach, doc sach, thuoc sach
sach hoc » cach hoc, sach hoi, mach hoc
cuu cong » cua cong, thu cong, cac cong
cong hoc » dong hoc, cong hoa, cong coc
hoc toan » hoc tan, hop toan, hoa toan
khoa hoc » hoa hoc
hoc dai » hoc dan
hai van » thai van, ha van, hai tan

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach hoc tap, nghien cuu cong hoc toan khoa hoc dai ((hoi va) OR (hai van)) thanh van~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach hoc tap, nghien cuu cong hoc toan khoa hoc dai ((hoi va) OR (hai van)) thanh van".
• Adding a wildcard symbol may retrieve word variants: toc sach hoc tap, nghien cuu cong hoc toan khoa hoc dai ((hoi va) OR (hai van)) thanh van*.