Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
van hanh » van thanh, ban hanh, van anh
sach tu » sach thu, cach tu, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
sach xu » sach xa, cach xu, mach xu
hieu va » lieu va, hieu qua
xuc van » duc van, luc van, vuc van
va cam » va cham, va cac, va cao

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 xu) or (sach tu)) nang mai hoi. hieu va cam xuc van hanh ((ki su) OR (ky su)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach xu) OR (sach tu)) nang mai hoi. hieu va cam xuc van hanh ((ki su) OR (ky su)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach xu) or (sach tu)) nang mai hoi. hieu va cam xuc van hanh ((ki su) OR (ky su)) triet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach xu) or (sach tu)) nang mai hoi. hieu va cam xuc van hanh ((ki su) OR (ky su)) triet*.