Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
benh de » benh ve, benh he, menh de
quoc co » quoc cao, quoc cho, duoc co
quoc bo » quoc bao, nuoc bo, quoc lo
van hau » van ha, van hai, van dau
lang xa » lang ha, dang xay, lang van
y lang » o lang, _ lang, tay lang
de cua » le cua, te cua, dieu cua
cua te » cua tu

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) or (toc sach)) y lang xa hoi. hieu van hau ((quoc bo) OR (quoc co)) benh de cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) y lang xa hoi. hieu van hau ((quoc bo) OR (quoc co)) benh de cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) y lang xa hoi. hieu van hau ((quoc bo) OR (quoc co)) benh de cua te".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) y lang xa hoi. hieu van hau ((quoc bo) OR (quoc co)) benh de cua te*.