432 A.W. Neumann new recommendations appear for a previously specified document. The usage of this service didn't meet the first expectations. Users seem to be skeptic about any service that tries to grab their attention(like spam mails)at times when they didn't even visit the library. To overcome this problem it is planned to extend this notification service in the near future to support RSS feed techniques. Thereby, each user can decide within the RSs reader when to poll the service. Further on, this way it is no longer connected to existing user accounts, but opened personalized service to the general public 3 Explicit Recommender Systems Two different kinds of explicit recommender systems are online at the University Library of Karlsruhe since March 2006, a rating service and a review service. To prevent fraudulent use, submitting ratings and reviews is possible only for logged- in users. These services differ from most other systems(e. g. Amazon coms) by means of user and target groups and strict separation of ratings and reviews Currently three different user groups exist: students(Studenten), university staff Mitarbeiter), and others(Externe)not directly associated with the universit While one could easily come up with more elaborate user classifications, these vices. They are checked(and afterwards tracked over time)by th ag these ser- three groups have been used by the library for many years prece e library for each user before handing out the library card. The guarantee of correctness made this user classification the(pragmatic) choice of approach for a library with an existing base of approximately 24 400 active users 3.1 Rating Service This service allows logged-in users so submit a numerical rating for a document on a Likert scale from 1 (very bad) to 5(very good). Every user can submit only one rating per document. The ratings are aggregated for each user group separately and are shown in numerical form(average rating, number of ratings) as well as an enlightened-star-graphic on the detailed document inspection page In figure I we see 4 ratings from students(Studenten) with an average of 3.5 and 5 ratings from university staff(Mitarbeiter) with an average 4.4. Thus, at a first glance[13 seems to be an overall good book, even more praised by scientists than by students Figure 3 shows the overall number of ratings online from 2006-03-03 to 2007 03-19. One large draw back of the current setup is known. Users searching the catalog are normally not logged-in until they want to order a paper copy of a document not freely available right now. To submit ratings they have to first log-in. This hurdle seems to have a huge influence on the number or submitted ratings, although it should have a very positive influence on the quality of the ratings. This service is best suited to get a first quick estimation of the overall quality of a document within certain user groups432 A.W. Neumann new recommendations appear for a previously specified document. The usage of this service didn’t meet the first expectations. Users seem to be skeptic about any service that tries to grab their attention (like spam mails) at times when they didn’t even visit the library. To overcome this problem it is planned to extend this notification service in the near future to support RSS feed techniques. Thereby, each user can decide within the RSS reader when to poll the service. Further on, this way it is no longer connected to existing user accounts, but opened as a personalized service to the general public 3 Explicit Recommender Systems Two different kinds of explicit recommender systems are online at the University Library of Karlsruhe since March 2006, a rating service and a review service. To prevent fraudulent use, submitting ratings and reviews is possible only for logged￾in users. These services differ from most other systems (e. g. Amazon.com’s) by means of user and target groups and strict separation of ratings and reviews. Currently three different user groups exist: students (Studenten), university staff (Mitarbeiter), and others (Externe) not directly associated with the university. While one could easily come up with more elaborate user classifications, these three groups have been used by the library for many years preceding these ser￾vices. They are checked (and afterwards tracked over time) by the library for each user before handing out the library card. The guarantee of correctness made this user classification the (pragmatic) choice of approach for a library with an existing base of approximately 24400 active users. 3.1 Rating Service This service allows logged-in users so submit a numerical rating for a document on a Likert scale from 1 (very bad) to 5 (very good). Every user can submit only one rating per document. The ratings are aggregated for each user group separately and are shown in numerical form (average rating, number of ratings) as well as an enlightened-star-graphic on the detailed document inspection page. In figure 1 we see 4 ratings from students (Studenten) with an average of 3.5 and 5 ratings from university staff (Mitarbeiter) with an average 4.4. Thus, at a first glance [13] seems to be an overall good book, even more praised by scientists than by students. Figure 3 shows the overall number of ratings online from 2006-03-03 to 2007- 03-19. One large drawback of the current setup is known. Users searching the catalog are normally not logged-in until they want to order a paper copy of a document not freely available right now. To submit ratings they have to first log-in. This hurdle seems to have a huge influence on the number or submitted ratings, although it should have a very positive influence on the quality of the ratings. This service is best suited to get a first quick estimation of the overall quality of a document within certain user groups