Perhaps you should try some spelling variations:
doanh hoa » doanh khoa, doanh hoan, danh hoa
sach hoc » cach hoc, sach hoi, mach hoc
cuu tong » cuu cong, cuu tinh, huu tung
so doanh » so danh, su doanh, hoa doanh
van phan » van phong, van thanh, luan phan
tu sach » thu sach, su sach, te sach
tong so » tuong so, thong so, tong son
xua hai » qua hai, cua hai, xa hai
xa thai » ca thai, a thai, da thai
phan va » phan van, nhan va, han va

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 tong so doanh hoa hoc ((xua hai) or (xa thai)) van phan va~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoc tap, nghien cuu tong so doanh hoa hoc ((xua hai) OR (xa thai)) van phan va.
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cuu tong so doanh hoa hoc ((xua hai) or (xa thai)) van phan va*.