Perhaps you should try some spelling variations:
trinh ve » trinh he, trinh va, trinh vi
lang mai » lang dai, lang hai, lang man
cua viet » ca viet, hoa viet, cua vat
va trinh » van trinh, va tinh, lap trinh
su sach » so sach, vu sach
co sach » bo sach, cuon sach, hoc sach
mai hoi » mai khoi, dai hoi, lai hoi
hieu ve » hieu va, hieu van
cac tuc » cac toc, cac tu, cac tac
ve cac » va cac, vien cac
tuc va » thuc va, truc va, tuc xa
y lang » o lang, _ lang, tay lang
thiet » thieu

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) or (co sach)) y lang mai hoi. hieu ve cac tuc va trinh ve ((cua viet) or (va thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (co sach)) y lang mai hoi. hieu ve cac tuc va trinh ve ((cua viet) OR (va thiet)).
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (co sach)) y lang mai hoi. hieu ve cac tuc va trinh ve ((cua viet) or (va thiet))*.