"Romeo and Juliet" by Shakespeare, 1597
"Romeo and Juliet" by Shakespeare, 1597 (available)

OK: Mary gets Romeo and Juliet
"Romeo and Juliet" by Shakespeare, 1597 (borrowed by Mary)    
"Merchant of Venice" by Shakespeare, 1600 (available)
Not available: it is borrowed by Mary
OK: Paul gets Merchant of Venice
Error: it has not been borrowed by Wendy
OK: Mary has returned Romeo and Juliet
OK: Paul gets Romeo and Juliet

"Romeo and Juliet" by Shakespeare, 1597 (borrowed by Paul)    
"Merchant of Venice" by Shakespeare, 1600 (borrowed by Paul)  
"A Midsummer Night's Dream" by Shakespeare, 1600 (available)  
"Through the Looking-Glass" by Lewis Carroll, 1871 (available)
"Alice in Wonderland" by Lewis Carroll, 1865 (available)      
No loan records
"Romeo and Juliet" by Shakespeare, 1597
"Merchant of Venice" by Shakespeare, 1600
No loan records