Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cao hoi » cau hoi, co hoi, cao hoc
truc va » thuc va, thuc vat, trung va
ve nam » he nam, le nam, te nam
va nam » van nam, ha nam, va nay
va dan » ca dan, va dao, va dau
ca dau » ca dao, ca dan, 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: tu sach ky nang cao hoi. hieu ((ve nam) OR (va nam)) truc va dan ca dau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang cao hoi. hieu ((ve nam) OR (va nam)) truc va dan ca dau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang cao hoi. hieu ((ve nam) OR (va nam)) truc va dan ca dau tren*.