Analysis of information sources in references of the Wikipedia article "三世佛" in Chinese language version.
When Buddhist Sanskrit texts refer to the buddhas of the three times, they always use the dvandva compound, i.e., atīta-anāgata-pratyutpannā buddhāḥ 'past, future, and present buddhas' or, rarely, atīta-anāgata-pratyutpannā sarvabuddhāḥ 'all past, future, and present buddhas.' In Chinese translations we find the equivalent of this in the form of 過去未來現在諸佛 (guoqu weilai xianzai zhu fu) 'buddhas of past, future, and present.' but we also commonly find the expression used in the Heart Sūtra, i.e., 三世諸佛 (san shi zhu fo) 'buddhas of the three times.' The exact Sanskrit equivalents of 三世佛 and 三世諸佛 i.e. tryadhva-buddhāḥ, tryadhvā buddhāḥ and tryadhva-sarva-buddhāḥ or tryadhvāḥ sarva-buddhāḥ are never found either as a compound or as individual words in Prajñāpāramitā texts.
When Buddhist Sanskrit texts refer to the buddhas of the three times, they always use the dvandva compound, i.e., atīta-anāgata-pratyutpannā buddhāḥ 'past, future, and present buddhas' or, rarely, atīta-anāgata-pratyutpannā sarvabuddhāḥ 'all past, future, and present buddhas.' In Chinese translations we find the equivalent of this in the form of 過去未來現在諸佛 (guoqu weilai xianzai zhu fu) 'buddhas of past, future, and present.' but we also commonly find the expression used in the Heart Sūtra, i.e., 三世諸佛 (san shi zhu fo) 'buddhas of the three times.' The exact Sanskrit equivalents of 三世佛 and 三世諸佛 i.e. tryadhva-buddhāḥ, tryadhvā buddhāḥ and tryadhva-sarva-buddhāḥ or tryadhvāḥ sarva-buddhāḥ are never found either as a compound or as individual words in Prajñāpāramitā texts.
