ErrorDocument 404 /404.shtml
RewriteEngine On 
RewriteRule ^html/([0-9]*).html sbook.php?bl_id=$1 [L]
RewriteRule ^html/([0-9]*)/index.html rbook.php?bl_id=$1 [L]
RewriteRule ^html/([0-9]*)/([0-9]*).html read.php?bl_id=$1&bu_id=$2 [L]
RewriteRule ^html/author/([0-9]*).html author.php?ba_id=$1 [L]




