Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
kham luc » khai luoc, kham cuoc, nhan luc
dau cua » day cua, cau cua, dan cua
su kham » su pham, vu kham, so kham
hieu su » hieu sau, tieu su, hieu so
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
luc va » duc va, tuc va, loc va
va dan » ca dan, va dao, va dau

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)) ky nang ma hoi. hieu su kham luc va dan ((dau cua) or (dai cua)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky nang ma hoi. hieu su kham luc va dan ((dau cua) OR (dai cua)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ky nang ma hoi. hieu su kham luc va dan ((dau cua) or (dai cua)) te".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ky nang ma hoi. hieu su kham luc va dan ((dau cua) or (dai cua)) te*.