Perhaps you should try some spelling variations:
quoc danh » quoc khanh, cuon danh, hoc danh
quoc quan » qua quan, luc quan, hoc quan
hanh tai » thanh tai, hang tai, han tai
lang mai » lang dai, lang hai, lang man
ky lang » ky nang, ky dang, ky tang
mai hoi » mai khoi, dai hoi, lai hoi
hieu va » lieu va, hieu qua
va chat » van chat, va phat, cao chat
cua tu » cua tuc, cua cu, cua te
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
cua su » qua su

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky lang mai hoi. hieu va chat ((quoc danh) or (quoc quan)) hanh tai ((cua tu) OR (cua su))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky lang mai hoi. hieu va chat ((quoc danh) OR (quoc quan)) hanh tai ((cua tu) OR (cua su)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky lang mai hoi. hieu va chat ((quoc danh) or (quoc quan)) hanh tai ((cua tu) OR (cua su))".
• Adding a wildcard symbol may retrieve word variants: tu sac ky lang mai hoi. hieu va chat ((quoc danh) or (quoc quan)) hanh tai ((cua tu) OR (cua su))*.