Perhaps you should try some spelling variations:
sach trien » sach tien, sach tren, sach thieu
thuoc sach » hoc sach, nuoc sach, thuat sach
trien nhi » trien nha, trien chi, trien thi
toc sach » hoc sach, doc sach, nuoc sach
nhi khoa » noi khoa, tai khoa, anh khoa
phoi hoc » hoi hoc, phoi thuoc, cho hoc
sach x » sach xa, sach xu, sach y
x phan » xa phan, d phan, a phan

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( toc sach trien nhi khoa hoc ) or ( thuoc sach x phan ((phoi hoc) OR (hoa hoc)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( toc sach trien nhi khoa hoc ) OR ( thuoc sach x phan ((phoi hoc) OR (hoa hoc)) ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( toc sach trien nhi khoa hoc ) or ( thuoc sach x phan ((phoi hoc) OR (hoa hoc)) ))*".