Perhaps you should try some spelling variations:
sang mai » sang ma, sang tai, lang mai
su sach » so sach, vu sach
ca viet » va viet, hoa viet, san viet
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
co viet » so viet, o viet, hoc viet
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
ky sang » ky nang, ky dang, ky tang
le nam » ly nam, he nam, le na
ve nam » he nam, va 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: su sach ky sang mai hoi. hieu ((ve nam) OR (le nam)) thuc va hanh vi ((ca viet) or (co viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky sang mai hoi. hieu ((ve nam) OR (le nam)) thuc va hanh vi ((ca viet) OR (co viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky sang mai hoi. hieu ((ve nam) OR (le nam)) thuc va hanh vi ((ca viet) or (co viet))".
• Adding a wildcard symbol may retrieve word variants: su sach ky sang mai hoi. hieu ((ve nam) OR (le nam)) thuc va hanh vi ((ca viet) or (co viet))*.