Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac
ban benh » san benh, ba benh, ban banh
quoc ban » quoc bao, quoc lan, quoc quan
nam quoc » nam duoc, nam buoc, nam thuoc
hieu van » hieu va, thien van, lieu va
lang xa » lang ha, dang xay, lang van
hoc anh » hoc nganh, hoc nhanh, ngoc anh
lai cua » dai cua, hai cua, lai chau
y lang » o lang, _ lang, tay lang
li cua » le cua, ly cua, di cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((hoc sach) or (hoc anh)) y lang xa hoi. hieu van nam quoc ban benh ((li cua) OR (lai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (hoc anh)) y lang xa hoi. hieu van nam quoc ban benh ((li cua) OR (lai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sach) or (hoc anh)) y lang xa hoi. hieu van nam quoc ban benh ((li cua) OR (lai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: ((hoc sach) or (hoc anh)) y lang xa hoi. hieu van nam quoc ban benh ((li cua) OR (lai cua)) tre*.