Geodesic
On quadratic irrationalities having continued fractions with small periods
Zapiski Nauchnykh Seminarov POMI, Analytical theory of numbers and theory of functions. Part 14, Tome 237 (1997), pp. 31-39 
E. P. Golubeva. On quadratic irrationalities having continued fractions with small periods. Zapiski Nauchnykh Seminarov POMI, Analytical theory of numbers and theory of functions. Part 14, Tome 237 (1997), pp. 31-39. http://geodesic.mathdoc.fr/item/ZNSL_1997_237_a3/
@article{ZNSL_1997_237_a3,
     author = {E. P. Golubeva},
     title = {On quadratic irrationalities having continued fractions with small periods},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {31--39},
     year = {1997},
     volume = {237},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1997_237_a3/}
}
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Voir la notice du chapitre de livre provenant de la source Math-Net.Ru

We study the class number of an indefinite binary quadratic form of discriminant $d$ based on the expansion of $\sqrt d$ into a continued fraction and single out sequences of $d$ for which $h(d)$ has a lower-bound extimate. Progress is made for the conjecture on the estimate of the quantity of prime discriminants $d$ with fixed length of period of expansion of $\sqrt d$.