With a cover teeming with cartoon pigs, a hit Chinese book reads, \"Taxi driver said, \'There are many beauties in your school, but they are expensive.\' ... The student answered, \'You get half off with a teacher\'s certificate.\'\" Boasting explicit phrases and branding ancient scholars as \"rogues,\" the book \"Those Who Don\'t Read It Upside-down Are Pigs\" might not be a children\'s classic, but online commenters claimed they bought the title for their kids, and their kids liked the book of humorous stories. In a bid to filter obscene and violent content in children\'s reading, the Chinese government on Thursday released a circular calling for stricter supervision over children\'s publications, a move many parents and publishers call \"imperative.\" \"The children\'s publications market has been thriving with many quality works that boost healthy development, but problems also exist, such as shoddy quality, improper content and overly high prices,\" said the document, which was jointly released by five departments including the Ministry of Education and the Publicity Department of the Communist Party of China Central Committee. The circular urged administrative departments to strictly ban publications that contain murder, violence, obscenity and erotic content. It also told publishing houses to train professional editing teams for children\'s titles. Xu Dexia, editor-in-chief of \"Literature for Children\" magazine, blamed unseemly books on some publishers\' pursuit of profits at the cost of cultural and social responsibility. Figures show that 523 of a total 581 Chinese publishing houses release books for children, and total publications in the genre soared to over 31,000 last year from 10,460 in 2007 -- an annual increase of 40 percent. While the traditional publication market keeps shrinking in general, Xu said, children\'s books remain one of the few profitable genres, and many publishers \"are digging into this last piece of cake.\" On the list of the country\'s top 100 best-sellers in the first half of 2013, children\'s books accounted for 52 titles. Other experts attribute the phenomenon to an increasingly flimsy society with more people obsessed with light-hearted entertainment. According to Thursday\'s circular, administrative departments should strengthen supervision and impose serious punishment on violators for printing, copying or releasing children\'s books with improper content. It also stressed online monitoring of information on harmful publications, calling for timely deletion of questionable digital publications and shutting down websites in severe cases. Prof. Fang Weiping at Zhejiang Normal University called for a rating system based on children\'s vocabularies and their abilities to perceive and accept. \"Children\'s reading quality ultimately depends on their parents\' and teachers\' judgement on children\'s books. They should introduce good books to the kids and guide their reading,\" said Sun Weiwei, an author of children\'s books.