Perhaps you should try some spelling variations:
tang dai » tang tai, tang dan, lang dai
van hanh » van thanh, ban hanh, van anh
dai hai » dai han, dai hoi, dai tai
hieu su » hieu sau, tieu su, hieu so
va hanh » va thanh, va danh, ban hanh
sac ky » sai ky
su cam » su nam, su cao, su can
vi cua » vai cua, di cua
cua tu » cua tuc, cua su, cua cu

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) or (cac ky)) tang dai hai. hieu su cam xuc ((va hanh) OR (van hanh)) vi cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sac ky) OR (cac ky)) tang dai hai. hieu su cam xuc ((va hanh) OR (van hanh)) vi cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sac ky) or (cac ky)) tang dai hai. hieu su cam xuc ((va hanh) OR (van hanh)) vi cua tu".
• Adding a wildcard symbol may retrieve word variants: tu ((sac ky) or (cac ky)) tang dai hai. hieu su cam xuc ((va hanh) OR (van hanh)) vi cua tu*.