Perhaps you should try some spelling variations:
hanh thanh » nhanh thanh, thanh thanh, khanh thanh
thanh dat » thanh san, thanh hai, thanh van
dang xay » dang van, van xay
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
xay hoi » xa hoi, tay hoi, cay phoi
ve chim » va chim, ve cham, ve chinh
va chat » van chat, va phat, cao chat
y dang » ky dang, 2 dang, _ dang
thiet » thieu

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) OR (su sach)) y dang xay hoi. hieu ((ve chim) or (va chat)) thuc hanh thanh dat va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) y dang xay hoi. hieu ((ve chim) OR (va chat)) thuc hanh thanh dat va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (su sach)) y dang xay hoi. hieu ((ve chim) or (va chat)) thuc hanh thanh dat va thiet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (su sach)) y dang xay hoi. hieu ((ve chim) or (va chat)) thuc hanh thanh dat va thiet*.