Charak Samhita
तत्रोपायाननुव्याख्यास्यामः- अध्ययनम्, अध्यापनं, तद्विद्यसम्भाषा चेत्युपायाः ॥६॥
The means for enhancing depth of knowledge are- study, teaching and discussion with authorities.
english translation
tatropAyAnanuvyAkhyAsyAmaH- adhyayanam, adhyApanaM, tadvidyasambhASA cetyupAyAH ॥6॥
hk transliteration by Sanscript