Perhaps you should try some spelling variations:
kinh kien » kinh dien, linh kien, dinh kien
cau tren » cu tren, dau tren, ca tren
kien cau » khien cau, hien cau, thien cau
sach ty » sach y, sach thu, xach tay
hieu va » lieu va, hieu qua
sach tu » sach thu, cach tu, sach uu
tuc va » thuc va, truc va, duc va
va cao » va cac, va co, va dao
x hoi » xa hoi, o hoi, x ho

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 ty) or (sach tu)) nang x hoi. hieu va cao ((tuc va) OR (tuc xa)) kinh kien cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ty) OR (sach tu)) nang x hoi. hieu va cao ((tuc va) OR (tuc xa)) kinh kien cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ty) or (sach tu)) nang x hoi. hieu va cao ((tuc va) OR (tuc xa)) kinh kien cau tren".
• Adding a wildcard symbol may retrieve word variants: te ((sach ty) or (sach tu)) nang x hoi. hieu va cao ((tuc va) OR (tuc xa)) kinh kien cau tren*.