Perhaps you should try some spelling variations:
trinh hoa » trinh do, trinh han
trinh doc » trinh do, trinh co, trinh hoi
va triet » va thiet, va trien, ve triet
dang xay » dang van, van xay
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
tuc va » thuc va, truc va, tuc xa

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 ky ((nang x) or (dang xay)) hoi. hieu va cac tuc va ((trinh doc) OR (trinh hoa)) va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang x) OR (dang xay)) hoi. hieu va cac tuc va ((trinh doc) OR (trinh hoa)) va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang x) or (dang xay)) hoi. hieu va cac tuc va ((trinh doc) OR (trinh hoa)) va triet".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang x) or (dang xay)) hoi. hieu va cac tuc va ((trinh doc) OR (trinh hoa)) va triet*.