Perhaps you should try some spelling variations:
khanh hoa » thanh hoa, hang hoa
sach hoc » cach hoc, sach hoi, mach hoc
cuu dong » cuu cong, cuu tong, cuu long
co khanh » co thanh, o khanh, co hanh
van gian » van giang, dan gian, van giao
gian dan » gian lang
tu sach » thu sach, su sach, te sach
xa hai » xa thai, xua hai, xa dai

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 dong co khanh hoa hoc ((xa hai) OR (xa hoi)) van gian dan~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach hoc tap, nghien cuu dong co khanh hoa hoc ((xa hai) OR (xa hoi)) van gian dan".
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cuu dong co khanh hoa hoc ((xa hai) OR (xa hoi)) van gian dan*.