Perhaps you should try some spelling variations:
kinh lao » tinh lao, kinh dao, trinh lao
sinh lao » tinh lao, sinh lam, sinh ly
khoa hoc » hoa hoc
hoach va » hoach xay, hanh va, doanh va
tu sach » thu sach, su sach, te sach
ba khoa » bia khoa, bao khoa, da khoa
va ba » va bai, va bao, va ban

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 ((kinh lao) OR (sinh lao)) khoa hoc ) or ( thu hoach va ba khoa hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach ((kinh lao) OR (sinh lao)) khoa hoc ) OR ( thu hoach va ba khoa hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu sach ((kinh lao) OR (sinh lao)) khoa hoc ) or ( thu hoach va ba khoa hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( tu sach ((kinh lao) OR (sinh lao)) khoa hoc ) or ( thu hoach va ba khoa hoc ))*.