Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
tru nang » tra nang, tri nang, truc nano
hanh tri » thanh tri, hanh tai, hanh trinh
va triet » va thiet, ve triet, cua triet
va trien » va truyen, va thiet, va tuyen
tu nang » tu nong, tu nano, tu lang
cac tuc » cac toc, cac tu, cac tac
xa hanh » xa thanh, xa khanh, va hanh

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 ((tu nang) or (tru nang)) xa hoi. lieu va cac tuc xa hanh tri ((va triet) OR (va trien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((tu nang) OR (tru nang)) xa hoi. lieu va cac tuc xa hanh tri ((va triet) OR (va trien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((tu nang) or (tru nang)) xa hoi. lieu va cac tuc xa hanh tri ((va triet) OR (va trien))".
• Adding a wildcard symbol may retrieve word variants: toc sach ((tu nang) or (tru nang)) xa hoi. lieu va cac tuc xa hanh tri ((va triet) OR (va trien))*.