Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
nang mai » nang ma, nang tai, lang mai
tan hanh » tan thanh, tang hanh, toan hanh
lang hai » lang chai, lang thai, lang ha
te sach » toc sach
hieu va » lieu va, hieu qua
cam duc » cam xuc, cao duc, pham duc
hanh ki » hanh vi, hanh ky, hanh kien
tu sach » thu sach, su sach, tu cach
va cam » va cham, va cac, va cao
ki su » ky 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 sach) OR (te sach)) vu ((nang mai) or (lang hai)) hoi. hieu va cam duc tan hanh ki su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) vu ((nang mai) OR (lang hai)) hoi. hieu va cam duc tan hanh ki su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (te sach)) vu ((nang mai) or (lang hai)) hoi. hieu va cam duc tan hanh ki su triet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (te sach)) vu ((nang mai) or (lang hai)) hoi. hieu va cam duc tan hanh ki su triet*.