@article{MOMA_1972__76_177619,
     author = {K.E. Hirst},
     title = {The {Length} of {Periodic} {Continued} {Fractions.}},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {428--435},
     publisher = {mathdoc},
     volume = {76},
     year = {1972},
     zbl = {0245.10005},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1972__76_177619/}
}