Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
ban benh » san benh, ba benh, ban banh
quoc ban » quoc bao, quoc lan, quoc quan
cam quoc » cac quoc, cao quoc, nam quoc
tu sach » thu sach, su sach, te sach
benh li » benh ly, benh lo, benh vi
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
li cua » lai cua, le cua, ly cua

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 xa) OR (nang ma)) hoi. ((hieu van) or (hieu va)) cam quoc ban benh li cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang ma)) hoi. ((hieu van) OR (hieu va)) cam quoc ban benh li cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang xa) OR (nang ma)) hoi. ((hieu van) or (hieu va)) cam quoc ban benh li cua tre*".