Perhaps you should try some spelling variations:
trinh vat » trinh van, trinh luat, sinh vat
san viet » gian viet, anh viet
sach ty » sach y, sach tu, sach thu
va viet » hoa viet, mai viet, dao viet
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
lang xa » lang ha, dang xay, lang van
ty lang » tay lang, ty xang, ty hang
luc va » duc va, tuc va, loc va
va cam » va cham, va cac, va cao

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 ty lang xa hoi. hieu va cam ((luc va) or (hoc va)) trinh vat ((va viet) OR (san viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty lang xa hoi. hieu va cam ((luc va) OR (hoc va)) trinh vat ((va viet) OR (san viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty lang xa hoi. hieu va cam ((luc va) or (hoc va)) trinh vat ((va viet) OR (san viet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ty lang xa hoi. hieu va cam ((luc va) or (hoc va)) trinh vat ((va viet) OR (san viet))*.