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

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) OR (va cam)) truc va dao ca ((dau tien) 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) OR (va cam)) truc va dao ca ((dau tien) 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) OR (va cam)) truc va dao ca ((dau tien) or (cu tren))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ma hoi. hieu ((ve cam) OR (va cam)) truc va dao ca ((dau tien) or (cu tren))*.