Perhaps you should try some spelling variations:
manh hai » lanh hai, minh hai, thanh hai
dan manh » dang manh, doan manh, van manh
thuc dan » thuc hanh, hoc dan, thuc vat
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
ca viet » va viet, co viet, hoa viet
nang co » nang cao, nang doc, nang noi
va nam » van nam, ha nam, va nay
nang o » nang ho, nang ro, nang x
hai ca » hai cua, hai ba, bai ca
ve nam » he nam, le nam, te nam

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 ky ((nang o) or (nang co)) hoi. hieu ((ve nam) OR (va nam)) thuc dan manh hai ca viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang o) OR (nang co)) hoi. hieu ((ve nam) OR (va nam)) thuc dan manh hai ca viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang o) or (nang co)) hoi. hieu ((ve nam) OR (va nam)) thuc dan manh hai ca viet*".