Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
hieu van » hieu va, thien van, lieu va
ve triet » va trien, su triet
hoc sac » hoc sach, hoc cac, hoc mac
mai hoi » mai khoi, dai hoi, lai hoi
cam duc » cam xuc, cao duc, nam duoc
va hanh » van hanh, va thanh, va danh
sac ky » cac ky, sai ky
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sac ky nang mai hoi. hieu van ((cam duc) OR (pham duc)) va hanh vi ((cua te) or (ve triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sac ky nang mai hoi. hieu van ((cam duc) OR (pham duc)) va hanh vi ((cua te) OR (ve triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sac ky nang mai hoi. hieu van ((cam duc) OR (pham duc)) va hanh vi ((cua te) or (ve triet))".
• Adding a wildcard symbol may retrieve word variants: hoc sac ky nang mai hoi. hieu van ((cam duc) OR (pham duc)) va hanh vi ((cua te) or (ve triet))*.