I REFER to Mr Alex Au Yeung's letter headlined, ''Study room needs staff'' (South China Morning Post, June 29). The opening hours of the students' study rooms in Urban Council Public Libraries are extended from the normal 57 hours to 91 hours per week during the examination period from April to June. During this period, the study rooms are open daily from 8am to 9pm, on a tri-session basis to students with valid admission cards. This arrangement has proved satisfactory and met the needs of the majority of students taking public examinations. During the examination period, the study rooms are always manned by library staff who regularly patrol them to maintain order. Concerning the behaviour of students in the Shui Wo Street Public Library, we have reminded staff to step up patrols in the study room and to deploy additional staff to supervise the study room if required. May I also appeal to students using study rooms to be self-disciplined and be considerate to others so as to maintain a quiet environment. Users are also welcome to report any irregularities to our staff to enable them to take immediate action. Should Mr Au Yeung have any further queries, he is welcome to contact me at 922 12690 or Ms Annette Ko, Assistant Librarian of Shui Wo Street Public Library, at 922 73058. LI CHOY LAI-CHUEN for Director of Urban Services