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 nhan » van phan, van thanh, danh nhan
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
nhan va » nhan tai, nhan dan, nhan tao

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 nhan 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 nhan 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 nhan va*.