Perhaps you should try some spelling variations:
hanh truc » hang truc, nhanh thuc, hanh thuoc
su sach » so sach, vu sach
truc va » thuc va, thuc vat, trung va
va hanh » van hanh, va thanh, va danh
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
mang xa » lang xa, mang may, dang xay
vi cuu » vinh cuu
vi luu » vi lua

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 ((mang xa) or (nang ma)) hoi. hieu va hanh truc va hanh ((vi cuu) OR (vi luu)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((mang xa) OR (nang ma)) hoi. hieu va hanh truc va hanh ((vi cuu) OR (vi luu)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((mang xa) or (nang ma)) hoi. hieu va hanh truc va hanh ((vi cuu) OR (vi luu)) tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((mang xa) or (nang ma)) hoi. hieu va hanh truc va hanh ((vi cuu) OR (vi luu)) tre*.