[#Knuth:1968]

[#Knuth:1968;]

[#Knuth:1981]

[#Knuth:1981;]

[#Knuth:1968,Knuth:1981]

5

[#Knuth:1968,Knuth:1981;]

[#Knuth:1981][#Knuth:1981]

[#Knuth:1981;][#Knuth:1981;]