Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
thu sach » thuat sach, thuoc sach, thu hoach
cam truc » cau truc, nam truc, lam truoc
tu sach » su sach, te sach, tu cach
truc va » thuc va, thuc vat, trung va
hieu ve » hieu va, hieu van
cu tren » tu tren, dua tren
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
ve cam » ve cham, ve cac, va cam

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