Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
duc tien » duc thien, luc tieng, thuc tien
hanh tai » hang tai, han tai, hinh tai
dang mau » dong mau, dang van, dang su
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
duc tre » duoc tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
mau hoa » cau hoa, ma hoa, mai hoa
ky dang » ky nang, ky danh
ve cac » va cac, vien cac

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 ky dang mau hoa. hieu ve cac nuoc va ((hanh tai) OR (thanh tai)) ((duc tre) or (duc tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky dang mau hoa. hieu ve cac nuoc va ((hanh tai) OR (thanh tai)) ((duc tre) OR (duc tien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky dang mau hoa. hieu ve cac nuoc va ((hanh tai) OR (thanh tai)) ((duc tre) or (duc tien))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky dang mau hoa. hieu ve cac nuoc va ((hanh tai) OR (thanh tai)) ((duc tre) or (duc tien))*.