Targeted s-gram matching: a novel n-gram matching technique for cross- and mono-lingual word form variants. - Ari Pirkola; Heikki Keskustalo; Erkka Leppänen; Antti-Pekka Känsälä; Kalervo Järvelin (Inf. Res., 2002)

The RATF formula (Kwok's formula): exploiting average term frequency in cross-language retrieval. - Ari Pirkola; Erkka Leppänen; Kalervo Järvelin (Inf. Res., 2002)

Non-adjacent Digrams Improve Matching of Cross-Lingual Spelling Variants. - Heikki Keskustalo; Ari Pirkola; Kari Visala; Erkka Leppänen; Kalervo Järvelin (SPIRE, 2003)

TREC 2003 Genomics Track Experiments at UTA: Query Expansion with Predefinded High Frequency Terms. - Ari Pirkola; Erkka Leppänen (TREC, 2003)