retain existing pdf bookmarks
i am new to this forum and have recently bought a prs 505. i have a manual in the form of a set of pdf files with each file with its existing bookmarks. when i tranfer one of these pdf files to the reader in pdf and lrf formats, it seems to lose those bookmarks leaving me with no option to browse the file. i am using calibre.
is there a way for me to retain those existing bookmarks???