@article{Trojanowski1978, 
     author = "Trojanowski, Anthony E.", 
     doi = "10.1137/0207039", 
     issn = "0097-5397", 
     journal = "SIAM Journal on Computing", 
     keyword = "algorithm,binary trees,binomial coefficient,k-ary tree,linear order,permutation,ranking", 
     link = "http://epubs.siam.org/doi/abs/10.1137/0207039", 
     month = "nov", 
     number = "4", 
     pages = "492--509", 
     title = "Ranking and Listing Algorithms for k -Ary Trees", 
     uri = "http://epubs.siam.org/doi/abs/10.1137/0207039", 
     volume = "7", 
     year = "1978", 
}

Problems: 400