Perhaps you should try some spelling variations:
thanh di » thanh doi, thanh de, thanh do
thuc dan » thuc hanh, hoc dan, thuc vat
thuc ban » thuoc ban, thu ban, thuc van
sach ty » sach y, sach tu, sach thu
su sach » so sach, vu sach
lang xa » lang ha, dang xay, lang van
su viet » so viet
va cam » va cham, va cac, va cao
di su » doi su, ki su, da su

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty ((nang x) or (lang xa)) hoi. lieu va cam ((thuc ban) OR (thuc dan)) thanh di su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((nang x) OR (lang xa)) hoi. lieu va cam ((thuc ban) OR (thuc dan)) thanh di su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((nang x) or (lang xa)) hoi. lieu va cam ((thuc ban) OR (thuc dan)) thanh di su viet".
• Adding a wildcard symbol may retrieve word variants: su sach ty ((nang x) or (lang xa)) hoi. lieu va cam ((thuc ban) OR (thuc dan)) thanh di su viet*.