Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
kham duc » pham duc, kham cuoc, pham duy
hanh de » hanh ve, hanh kem
va hanh » van hanh, va thanh, va danh
vu kham » vu khanh
hieu vu » hieu va, hieu ve, hieu su
tu sach » thu sach, te sach, tu cach
tu nong » tu dong, tu cong, tu tong
tu nang » tru nang, tu nano, tu lang
su sach » so sach, vu sach
de su » den su, ve su, de tu

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) or (su sach)) ((tu nang) OR (tu nong)) x ho. hieu vu kham duc va hanh de su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ((tu nang) OR (tu nong)) x ho. hieu vu kham duc va hanh de su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ((tu nang) OR (tu nong)) x ho. hieu vu kham duc va hanh de su triet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ((tu nang) OR (tu nong)) x ho. hieu vu kham duc va hanh de su triet*.