Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
su triet » su viet, su tien, ve triet
tinh doi » trinh doc, trinh do, tinh hoc
hieu van » hieu va, thien van, lieu va
ly quang » le quang, vu quang
van cac » van hac, van cau, van bac
cac tuc » cac toc, cac tu, cac tac
va tinh » may tinh
do hoi » do choi, do hoai, do thoi
tuc va » thuc va, truc va, tuc xa
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: toc sach ((ly hang) or (ly quang)) do hoi. hieu van cac tuc va tinh doi ((su triet) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ly hang) OR (ly quang)) do hoi. hieu van cac tuc va tinh doi ((su triet) OR (cua te)).
• Adding a wildcard symbol may retrieve word variants: toc sach ((ly hang) or (ly quang)) do hoi. hieu van cac tuc va tinh doi ((su triet) or (cua te))*.