Perhaps you should try some spelling variations:
cam truc » cau truc, lam truoc, nam truoc
dau tren » dau tien, dat tren, dau tieng
nam truc » nam truoc, nam thuc, nam trung
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cu tren » tu tren, dua tren
hieu ve » hieu va, hieu van
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
va dao » ca dao
dao ca » dao cac, dao cao, dao cau

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 ky nang ma hoi. hieu ve ((cam truc) OR (nam truc)) va dao ca ((dau tren) or (cu tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ma hoi. hieu ve ((cam truc) OR (nam truc)) va dao ca ((dau tren) OR (cu tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ma hoi. hieu ve ((cam truc) OR (nam truc)) va dao ca ((dau tren) or (cu tren))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ma hoi. hieu ve ((cam truc) OR (nam truc)) va dao ca ((dau tren) or (cu tren))*.