Perhaps you should try some spelling variations:
kham thong » khap thong, khau thong, pham thuong
sach tren » sach tien, sach tranh
xanh khoa » anh khoa, doanh khoa, nganh khoa
khoa kham » kho khan, khoa than
cac khoa » cac khoan, cac khoi, dac khoa
te sach » toc sach
tren ve » tren xe, tren he, tren vi
ve xanh » ve canh, ve hanh, ve thanh
su sach » so sach, vu sach
khoa he » hoa he, khoa hoc, khong he
tri ve » tri le, trinh ve

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( te sach tren ve xanh khoa kham thong ) or ( su sach ((tri ve) OR (tri va)) cac khoa he thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( te sach tren ve xanh khoa kham thong ) OR ( su sach ((tri ve) OR (tri va)) cac khoa he thong )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( te sach tren ve xanh khoa kham thong ) or ( su sach ((tri ve) OR (tri va)) cac khoa he thong ))".
• Adding a wildcard symbol may retrieve word variants: (( te sach tren ve xanh khoa kham thong ) or ( su sach ((tri ve) OR (tri va)) cac khoa he thong ))*.