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2. Birzaka, J. (1940). Vçrojumi augïu dârzos Mâlpils rajonâ 1940. gada vasarâ [Observations in orchards in Mâlpils region in the summer of 1940]. Dârzkopîbas un Biðkopîbas Þurnâls, 10, 531 (in Latvian).
3. Delle, P. (1938). Materiâli un ierosinâjumi vietçjâs augïkopîbas, augïu vçrtçðanas un izvçrtçðanas jautâjumos [Materials and suggestions about the problems of local fruit-growing and fruit evaluation]. Dârzkopîbas un Biðkopîbas Þurnâls, Nr. 3, 93-101, Nr. 6, 225-233, Nr. 9, 362-365 (in Latvian).
4. Dindons, P. (1929). Kas jâievçro turpmâk pie augïu dârzu ierîkoðanas [What should be observed at establishment of orchards in future]. Rîgas dârzkopîbas biedrîbas gada grâmata, 75-78 (in Latvian).
5. Gailītis, P. (1940). Kârïos atrodamais potcelmu materiâls [Rootstock material found at Kârïi]. Dârzkopîbas un Biðkopîbas Þurnâls, Nr. 9, 467-473 (in Latvian).