Perhaps you should try some spelling variations:
nhien cac » hien cac, thien cac, hieu cac
su triet » su viet, su tien, ve triet
toc sach » hoc sach, doc sach, thuoc sach
vien cac » vien bach, vien dai, vien da
dan van » dang van, doan van, dao van
nang ma » tang ma, sang ma, nang cao
y nang » ky nang, ly nang, v nang
xuc va » duc va, tuc va, luc va
va dan » ca dan, va dao, va dau
van su » dan su

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) y nang ma hoa. thien ((nhien cac) or (vien cac)) xuc va dan van su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) y nang ma hoa. thien ((nhien cac) OR (vien cac)) xuc va dan van su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) y nang ma hoa. thien ((nhien cac) or (vien cac)) xuc va dan van su triet".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) y nang ma hoa. thien ((nhien cac) or (vien cac)) xuc va dan van su triet*.