引用书的简称

Question

我想知道如何引用一本书的简称。例如：

@book{Blackstone59, 
   Address = {London}, 
   Author = {Blackstone, William}, 
   Date-Added = {2017-03-15 11:58:40 +0000}, 
   Date-Modified = {2017-03-15 11:59:24 +0000}, 
   Publisher = {Cavendish Publishing}, 
   Title = {{Commentaries on the Laws of England}}, 
Shorttitle = {{Commentaries}},
   Volume = {1-4}, 
   Origdate = {1765-9}, 
   Year = {2001}}

我必须自己定义命令吗？如果是这样，我该怎么做？我不明白你如何自己定义命令，例如\citeshorttitle{Blackstone59}。