Dictionary software generally far exceeds the scope of the hand held dictionaries. Many publishers of traditional printed dictionaries such as Langenscheidt, Collins-Reverso, OED Oxford English Dictionary, Duden, American Heritage, and Hachette, offer their resources for use on desk top and lap top computers. These programs can either be downloaded or purchased on CD-ROM and installed. Other dictionary software is available from specialised electronic dictionary publishers such as iFinger, Abbyy Lingvo, Collins-Ultralingua, Mobile Systems and Paragon Software. Some electronic dictionaries provide an online discussion forum moderated by the software developers and lexicographers.