1. Common information is far less than mutual information;Gács;Problems of Control and Information Theory,1973
2. Three approaches to the quantitative definition of information;Kolmogorov;Problems in Information Transmission,1965
3. On the extraction of common information of two words;Muchnik,1986
4. The complexity of finite objects and the algorithmic concepts of information and randomness;Zvonkin;Russ. Math. Surv.,1970